So for todays 12.10 appt at the drs, I was ready by 11.30, out the door at 11.40 and there by 12
I would also be there by 12. Actually it's ridiculous because what GP is ever running to time? But if I arrived at 12.15 they'd refuse to see me. So I have to make sure I am on time.
Likewise, trains and planes will go without me. So the risk of missing a flight is massively stressful for me, so I make sure I eliminate the possibility as far as is reasonable without getting to the airport 5 hours before.
When I worked in London I didn't get a ridiculously early train to make sure I was never late for work, but I did get one that was 10 minutes earlier than another. Most of the people on here who are late would get the later one, or possibly the one after that.
For a one-off meeting, I would go earlier.
Yes it means I might have to kill time in a cafe. But it would be very unprofessional to arrive late because I didn't consider the very real possibility that my train would be late.
Some of you are also missing the point that many people are late all the time because it suits their narrative of being incredibly busy people. There are workplaces where everyone is late for meetings (except me :) ) because it looks uncool to be on time, as you can't be busy!