I reckon in a lot of cases, where the ejected punter is leglessly drunk, they similarly wouldn’t have a leg to stand on when it comes to legal action.
When my brother worked as a barman in Cape Town, one tactic they would use before calling in the bouncer was to offer the troublesome customer a complimentary “paddle” - a board with seven slots for seven shots of liquor, normally some sort of white spirit, which were to be downed in quick succession. The last 2 or 3 of these would be replaced with “witbllitz” (literally “White Lightning”), a South African distilled (often homebrewed) grape liquor, usaually over 80% proof.
No trouble-causer would turn down free alchohol, but once they got the end of the paddle, one of two things would usually happen - either they would rush to the bathroom and hurl thier guts out for a while, which generally took the wind out of their sails, or they would go very quiet and quite pale and not make a noise again all night.
Grim
True, perhaps why bouncers here in the UK (that I’ve seen) can get away with hauling a disorderly patron outside of the bar. I was always reminded at jui-jitsu classes that the mere act of grabbing someone by their clothing was assault, so it seemed to me that bouncers, lacking the authority of the police, chuck someone out and rely on them being plastered, not physically injured and possibly in the wrong for other reasons not to turn around and call the police to explain.