Ground movements and runway clearances are still very manual processes unfortunately, and mistakes happen especially in high task-load situations or poor visibility or flight number collisions etc. The safe part about being in the airplane is actually being in the air, lol - once you push back you are at fairly elevated statistical risk until you’ve got some altitude. Takeoff/landing are high risk and there’s a lot of people and a lot of chances for mistakes on the tarmac.

There are statistically an enormous number of ground movements carried out safely but boy does the potential body count get big with runway incursion scenarios. Two 757s colliding is a lot of people, and in high-energy scenarios at least one of the aircraft isn’t walking away. You can be doing nothing wrong and someone just landings on your taxiway etc. The close calls are terrifying.