Exactly. Tower can literally be a mile away at times, even using the binoculars they haven't got a hope of seeing if 2 aircraft passing at awkward angles have sufficient clearance. Only those on the aircraft are close enough. Sensors in the stop bars detecting if someone's A**e is hanging out might help some of the problem, but with all the mixture of aircraft types and wingspans etc, it wouldn't make an enormous difference
Just thinking out loud here.
I was considering the good, 'ole xpdr and thinking that maybe it could help ground control to better monitor the situation on tways and rways.
Instead of using it only up in the air, we could use it on the ground as well.
Get a dedicated code for ground ops so the ground controller knows exactly where you are at all times.
Once you're on the rway, switch to the "air" code.
Pretty much everything is already in place, we just need to use it a bit differently.