[input_sh]

Oh I can think of many others: cryptocurrency exchanges, many payment providers, some server providers, Twitter (during verification), freelancing platforms (like Upwork) and even Pornhub.

Sometimes it's a legal obligation (under KYC), sometimes it's pressure from credit card companies, and sometimes it's just websites making shit up to enforce their own rules.

[winternett]

Crypto exchanges do it because of mandated government income tax reporting requirements and potential for payment fraud (also a regulated industry).

Twitter requires ID and personal information (i.e. your phone number) for verification even from users that are not involved in any sort of purchasing or income scenarios.

Reddit started out not caring about who anyone was, but over time IP based tracking and other things started to creep in...

Private companies that aren't regulated nor involved in conducting regulated business should not be asking for any government issued ID nor personal user data if you ask me.