They obviously need stronger buses!
I think this kind of incident is going to happen every now and then, just due to statistical likelihood. All the holes lined up: environmental conditions, positions of the buses and aircraft, power settings, etc. Change any one of those and it wouldn’t have happened.
I notice that one of the engines was at 0%. It’s SOP to shut down an engine if you can where I work, unless there are good reasons not to. Personally, I keep them all running unless I can manoeuvre onto stand without increasing power in the turn (777). It’s not just windows on buses, imagine what could happen if an empty cargo container got hefted across the apron - it could easily kill people. The amount of junk that gets left around the edges of parking areas makes this kind of thing a distinct possibility at many airports...