"what we got was the TPS, an opt-out system with no real teeth."
Even worse, the PAPER junkmail optout system has to be opted out of every 2 years (not MPS, the royal mail system for fliers)
I'm surprised the legality of that hasn't been challenged sinve GDPR laws changed
https://personal.help.royalmail.com/app/answers/detail/a_id/293/~/how-do-i-opt-out-of-receiving-any-leaflets-or-unaddressed-promotional-material%3F
In the USA you have Form 1500 and Rowan vs USPS, which HAS teeth.