It also helps verify against people causing damage to the hotel. Business where the transaction is not a simple "seller provides item - buyer pays seller" have different risks involved, and therefore need to additional measures to protect against them.
Requiring credit cards, government issued photo ID, age over 21 are all methods of preventing guests who trash rooms, sneak in pets and cause noise disturbances, underage partiers, pimps and hookers, drug dealers, excessively dirty and causing pest problems etc from messing up the business. Same with car rentals and flights. Some people are problematic, and it affects other customers, and you need a way to mitigate the problem.
In the US, almost all local ordinances require hotel operators to keep track of who is staying in which room for a year or so (some even require photocopying, although that's not always followed), and to hand over that info to police whenever they demand it.
Requiring credit cards, government issued photo ID, age over 21 are all methods of preventing guests who trash rooms, sneak in pets and cause noise disturbances, underage partiers, pimps and hookers, drug dealers, excessively dirty and causing pest problems etc from messing up the business. Same with car rentals and flights. Some people are problematic, and it affects other customers, and you need a way to mitigate the problem.
In the US, almost all local ordinances require hotel operators to keep track of who is staying in which room for a year or so (some even require photocopying, although that's not always followed), and to hand over that info to police whenever they demand it.