Usually I find if you remove the valve core & use an air duster with a large hole, the air will enter fast enough to make a seal on the beads.
Some times I need to pu a strap around the tyre and even jiggle it back & forth to get the beads to touch some thing solid & take.
The reason for the small air tank tyre inflators is to prevent injury to the tyre fitter .
Most tyre shops and a lot of workshops will have a large air receiver on the end of the compressor .
Mine is around 100 gallons.
So if some thing goes wrong, 100 gallons of air at 150PSI will instantly try to become 100,000 gallons of air at normal atmospheric pressure which is effectivly a bomb.
It is ot odd for a tyre shop to have compressors running 200 psi so the fitters can not draw air faster than it can be supplied and you don't want to be around when that lets go.