three quarters of the downtown towers i delievered to didn't give a crap over which door or elevator i used. a quarter had policies that service door and elevator had to be used, but they just gave up after all the bike couriers would defy them, or security realized that their lives have no purpose in life, beyond yelling at people with more meaningful and higher paying jobs, unaware that people with business to conduct downtown don't mind seeing the courier riff-raff.
but there's one building where they will chase you and physically prevent you from boarding an elevator, even if you walk fast and don't turn around when they yell. even giving them the "oh i'm so sorry sir, you're doing a great job. it's my first day and i don't know better and if i don't get these off on time i'll be out of a job and my 2 adopted refugee children won't have anything to eat" line won't get you on.
to bring the stupid policy into disrepute (and so i could do my job properly), i only used the elevator to go up to the top floor, because they only have 1 elevator for 40 storeys, i would use the grown-up elevators to go down and finish my run. to piss off the useless security guard, i would exit the building with my trolley using the elevator for grown-ups wishing the security goon a nice day and to enjoy the lovely weather from behind his desk.