Licensed operators are legally required to verify age and identity, and to question the source of funds when deposits warrant it, under anti-money-laundering rules. In Great Britain, the Gambling Commission's licence conditions require age and identity verification before a customer can gamble at all.
In practice the friction often lands at withdrawal: an account that deposited freely is asked for documents when money moves the other way. That sequencing is a business choice and a fair complaint. The check itself is not: an operator that never asks who you are is not being generous, it is telling you which rules it does not follow.
Why it matters
KYC is the visible edge of the licensing system. Sites advertise 'no KYC' as a feature; read as a signal, it means no age checks, no money-laundering controls, and no regulator to complain to when a withdrawal never arrives.
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