The guy was alone operating 2 frequencies, had an emergency of another aircraft going on… is not so easy as many commenters from the armchair are insinuating
(See my other comment below if you're tempted to say something about visibility.)
When cleared across a runway I'm still going to be looking in all directions, and proceed as fast as I can. I also look both ways at railway crossings even if the guards are up and silent.
I also wonder if you're down to a "one controller" scenario if it would be better for there to be once frequency, not a ground/air split.
I'm not saying its easy, I'm actually specifically saying it's such a hard job we should have automated most of it away ages ago. If the only thing stopping an accident like this is an ATC employee, this _will_ happen in the future.
They came up with rail signals long before the idea of a computer even existed. It's hard to believe voice only communication of routes and runway access is the best path forward. Especially when passenger airliners are involved.
Automation is fantastic. We use it extensively in aviation. However, the long tail of 9s in reliable requires constant vigilance and oversight because anything that can go wrong will.
There are so many failure modes with vehicles and planes using the same tarmac that I fail to see how anything would be worth developing here that doesn't eliminate that requirement altogether.
Presumably this is lack of familiarity with this on the part of firefighters.