I prefer pull-through spots when shopping, but would generally rather back in than back out, because I can see where everyone is right before I back in. If I'm backing out, I've been putting my bags in the car, fussing with my seatbelt, the radio, whatever... so there is a gap of time where pedestrians could walk up near the car without me seeing them.
This is even more true for school pick-up. We're arriving over a period of around 20 minutes, backing in when it's just cars, but we're all leaving at the same time, with kids walking through the lot, so I feel like it's much safer to be pulling forward.