I don't know when you did this, but you can't buy a ticket on a train (not subway) in China without providing identification in any city someone would recognize (Beijing, Shanghai, Shenzhen, Xiamen, Chongqing, etc.). As a foreigner, if you exit any of those cities in a car, you must notify the authorities (which is a pain when the Factory is just outside... but the manufacturer will let you know before they let you stay).

This has been largely true for the last 10 years. The same is true for any bus that crosses provincial boundaries. That includes every major Chinese train station (excluding HK/TW) in every city most people can name. If someone else bought you a ticket, they put a fake (probably western) ID on it or they did a favor of using your ID without telling you (that's why they ask for your Passport#). Even the standard electronic purchase stalls only print out a ticket if you provide a China ID, or in a small number of cases a Passport. Everywhere else you have to stand in line to provide ID to the ticketing agent.

All patrons of a hotel must provide an ID (even if you are a non-paying guest) to check in. If it is a foreign ID, they must photocopy it and provide it to the authorities (including your visa information). If you stay at an AirBnB, you must check in at the local Police Station with your Passport/Visa. Not doing so is a crime punishable by imprisonment and revocation of your visa!