If they're a monopoly in a sector where you could conceivably compete, you can be pretty sure they are buttressed by regulations, lobbying, and legal precedent that will put you in a world of hurt before you get far.
Not sure how repeatable ignoring laws are in battling monopolies.
That being said, I wonder how much money the founders spent on private security for themselves meanwhile?
Unions (including taxi unions) are known to play funny buggers in the real world against those they perceive as threats.