Dave:
OK, now I get it.
As Bob said, Sq D has Power Link.
And, you have the shunt trip option on many other brands, but not 'remote-ON' that I'm aware of. ST indicates trip at the CB, and the handle does the reset.
Your key lock setup seems to cover LOTO...but as Bob said...tradition.
I wonder why?? Push-A-matic went by the wayside?? Heck, I even have some OLD 3-pole Bulldogs laying in the shop.
As to UL, Reno's on the track...trip indication, reset capabilities, etc.
John