Yeah, but laws tend to be more constant, and lawful interception laws are, 100% guaranteed, a thing, right now, in the country where you live.

They apply to telegrams, postal mail, telephone conversations, and a whole bunch of other things nobody really does anymore. They don't really apply to the things people do tend to do these days.

ChatControl is an incompetent attempt to remediate the lapses in law enforcement that this has caused. I strongly oppose it. But I also strongly oppose the idea that the Internet should be off limits for any kind of law enforcement, unless it is through dubious mechanisms like state-sponsored malware.

Your "slippery slope" argument is much more compelling in the absense of extended lawful interception than in the situation where Signal messages would somehow be equated to postcards or SMS messages...