I don't usually have a problem getting on the bike. It's getting off with something large on the back rack. That was a small part of my motivation to get a dedicated cargo bike. Falling off a stopped bike when your feet aren't even clipped in place makes you feel pretty silly.
I have a lot of trouble reliably, safely stepping over the top tube. Something about the size of my feet and how long my legs are makes it pretty hard to get my foot over. It's even worse if the bike is heavily loaded so tilting is difficult.