> Why are these service providers being punished for what their users do?
There is a legal distinction here between what happens on your platform despite your best efforts (what you might call "incidental" use) vs what your platform is designed specifically to do or enable.
Megaupload is a perfect example. It was used to pirate movies. Everyone knew it. The founders knew it. You can't really argue it's incidental or unintended or simply that small amount that gets past moderation.
Telegram, the authorities will argue, fails to moderate CSAM and other illegal activity to the point that it enables it and profits from it, which is legally indistinguishable from specifically designing your platfrom for it.
Many tech people fall into a binary mode of thinking because that's how tech usually works. Either your code works or it doesn't. You see it when arguments about people pirating IP being traced to a customer. Tech people will argue "you can't prove it's me". While technically true, that's not the legal standard.
Legal standards relay on tests. In the ISP case, authorities will look at what was pirated, was it found on your hard drive, was the activity done when you were home or not and so on to establish a balance of probabilities. Is it more likely that all this evidence adds up to your guilt or that an increasingly unlikely set of circumstances explains it where you're innocent?
In the early days of Bitcoin I stayed away (to my detriment) because I coudl see the obvious use case of it being used for illegal stuff, whichh it is. The authorities don't currently care. Bitcoin however is the means that enables ransomware. When someone decides this is a national security issue, Bitcoin is in for a bad time.
Telegram had (for the French at least) risen to the point where they considered it a serious enough issue to warrant their attention and the full force of the government may be brought to bear on it.