Am I missing something here?
So it takes no longer for me to check in at the airport and let them do it all for me.
depends on so much, what airline you’re on, the airport, where you are going, the time of day, the Passenger service agent you see.
for example I used to do bag drop for Virgin at LHR T3. If it was quiet and you come to me not checked in with a US passport going to the states, it’s quicker to check you in then explain/persuade you to go use a self self kiosk to checkin. At rush hour, a family of 5 with UK/Nigerian/china etc going to the states it takes so long with Visa/ESTA, covid, hotel address, next of kin etc to check you in I’d tell you to go use a kiosk. If you are nice and have little baggage I might let you jump the queue when you come back.
if the queue for bag drop is long and taking a long time, often it’s because people haven’t checked-in in advance and the agents are doing it for them which normally they shouldn’t be