Cookie alternatives were supposed to fix privacy problems. Instead, they’ve created worse ones. The UK Information Commissioner’s Office called Google’s December 2024 fingerprinting policy “irresponsible”—the same fingerprinting that’s been positioned as the cookie replacement. Here’s the uncomfortable truth: simple first-party cookies with proper consent are now the more privacy-respecting choice.

The industry spent years demonizing cookies. Now the “solutions”—fingerprinting, Universal IDs, Topics API—face the same scrutiny, except they’re harder to control, impossible to delete, and require infrastructure most small businesses can’t afford.

The Cookie Replacement Problem

When browsers started blocking third-party cookies, the advertising industry scrambled for alternatives. Three main approaches emerged: device fingerprinting, Universal ID systems like UID2, and Google’s Privacy Sandbox. Each promised to solve tracking while respecting privacy.

None delivered on that promise.

Device fingerprinting collects browser attributes, screen resolution, fonts, timezone, and IP address to create a unique identifier. It works even when cookies are blocked. That’s the selling point—and the problem.

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As the UK ICO stated in December 2024: “Even if you ‘clear all site data’, the organisation using fingerprinting techniques could immediately identify you again. This is not transparent and cannot easily be controlled.”

Translation: cookies give users a delete button. Fingerprinting doesn’t.

What the UK ICO Actually Said

Google announced in December 2024 that it would allow advertisers to use fingerprinting starting February 16, 2025. The UK’s data protection authority responded within days, calling the policy change “irresponsible.”

Stephen Almond, ICO Executive Director of Regulatory Risk, didn’t mince words: “We think this change is irresponsible. Google itself has previously said that fingerprinting does not meet users’ expectations for privacy.”

This matters because Chrome holds over 60% of global browser market share (Fingerprint.com, 2024). Google’s policy decisions shape the entire advertising ecosystem.

The ICO’s official position is clear: “Fingerprinting is not a fair means of tracking users online because it is likely to reduce people’s choice and control over how their information is collected.”

GDPR fines have reached €5.88 billion as enforcement accelerates around fingerprinting and tracking technologies (Secure Privacy, 2025). Regulators aren’t just issuing warnings—they’re writing checks.

The Universal ID Scale Problem

Universal ID 2.0 (UID2) takes a different approach. Instead of tracking device attributes, it creates encrypted identifiers from email addresses or phone numbers. Sounds cleaner, right?

Here’s the catch: it only works when users log in.

For publishers running content sites, that’s a viable model—readers might create accounts for premium content. For e-commerce stores where casual browsers outnumber logged-in shoppers 10:1? The math doesn’t work.

Apple’s App Tracking Transparency (ATT) showed what happens when you ask permission. ATT opt-in rates sit at 35% industry-wide as of Q2 2025 (Adjust, 2025). In privacy-conscious Germany, it’s just 20% (Adjust, 2023). Two-thirds of users say no when given the choice.

You may be interested in: Universal IDs, UID2, and Hashed Emails: The Cookie Alternatives Big Ad Tech Uses

UID2 requires that same explicit consent—plus a login. Publishers anticipate up to 60% ad revenue declines without effective cookie alternatives (Secure Privacy, 2025), but UID2 doesn’t solve conversion tracking for stores where most visitors never create accounts.

Why First-Party Cookies Became the Ethical Choice

Here’s the irony: the simple first-party cookie is now the privacy-respecting option.

First-party cookies work only on the domain that sets them. Your WooCommerce store’s session cookie can’t follow customers to other websites. It remembers their cart, tracks their purchase, then stays in its lane.

That’s exactly how Lou Montulli designed cookies in 1994. Third-party advertising cookies corrupted the original intent. First-party cookies for your own site’s analytics? That’s using the technology as intended.

The distinction matters:

• First-party cookies: Set by your domain, work only on your domain, can be deleted by users, require consent under GDPR
• Fingerprinting: Works across all domains, persists after clearing data, cannot be deleted, regulators call it “irresponsible”
• Universal IDs: Require login infrastructure, only work for authenticated users, scale problems for e-commerce

67% of B2B companies already adopt server-side tracking, achieving 41% data quality improvements (Secure Privacy, 2025). They’re not replacing cookies—they’re enhancing first-party data collection with server-side delivery that bypasses ad blockers.

What WordPress Store Owners Actually Need

Store owners don’t need to track visitors across the internet. They need to know: did this ad click become a purchase?

That question doesn’t require fingerprinting. It doesn’t require Universal ID infrastructure. It requires connecting the customer’s email address—which they provide at checkout—to the ad click that brought them.

Here’s the practical approach:

• First-party cookies: Track sessions on your site with proper consent
• Server-side event delivery: Send conversion data from your server, bypassing ad blockers
• Hashed email matching: Connect purchases to ad platforms using SHA256-hashed customer emails

This is simpler than fingerprinting, cheaper than UID2 infrastructure, and more privacy-compliant than either.

Transmute Engine™ takes this approach—a first-party Node.js server running on your subdomain that captures WooCommerce events and routes them to GA4, Facebook CAPI, Google Ads, and BigQuery simultaneously. No fingerprinting, no Universal ID dependencies, just legitimate first-party data with proper consent.

Key Takeaways

• UK ICO called fingerprinting “irresponsible”—it cannot be cleared like cookies and removes user control
• UID2 requires login infrastructure—a scale problem for e-commerce where most visitors don’t create accounts
• ATT opt-in rates are 35%—two-thirds of users reject tracking when asked
• First-party cookies with consent are now the privacy-respecting choice for WordPress stores
• Server-side tracking with hashed emails achieves conversion attribution without invasive techniques

Ready to track conversions without privacy nightmares? Seresa’s first-party approach gives you accurate attribution using the data customers already share at checkout.