Originally Posted by
speedbuslhr
Pretty sure you need some kind of ID to check in a bag seems pretty reasonable, otherwise anyone could check in a bag under your name if they got hold of your boarding pass.
also if at the gate it could be an issue with the biometric gates hence an ID check, quite common at Heathrow when the gates fail.
You don't for domestics, unless they're checking in firearms.
Although sometimes it's hard to remember that, especially if you're in a situation like LHR T5 or T3 where you're handling all sorts of flights. When I was a check-in agent there had been times when I mistakenly asked for ID a passenger going to, say, GLA.
One possibility as to why people are being asked for ID at the gate (in T5, don't know about elsewhere) is that the biometrics are taken at the entry point of security, where you scan the BP before proceeding to the actual security check; the system there is now asking people to lower their masks but, to be honest, I always forget about it (and frankly I don't fly on a lot of Domestics so I don't know whether not doing that might stop you).