I was only with him once when this happened, and the station manager appeared and said I could lead him (without a ticket) and he'd let me out when I came back, which he did. My friend said it happened every month or two. Going alone meant he risked tripping on stairs, especially if it was busy and people jostled him.
But more importantly the wage negotiations are very complicated as 80% of the money ultimately comes from the government and therefore politicians needs to be motivated. Politicians are mostly motivated by annoyed voters (and campaign contributions obviously).
Around 20% is commercial income (advertising, levies on new commercial buildings).
https://board.tfl.gov.uk/documents/s19826/TfL%20Budget%20202...
I've never seen a barrier hopper stopped, but I'm sure the bobbies would be sent in if thry announced everyone would be doing it.
There's also the problem of disconnected services - the purple line is Rail, so while they use the same stations, they can be on strike when the Underground isn't. So you could go through open barriers at a rail station but you'd find the barriers shut trying to leave from an Underground station.
While most of the train strikes over the last year have been RMT primarily, ASLEF and TSSA did vote to strike in support of RMT during the winter. They're both part of the TUC after all.
https://www.cityam.com/newest-strike-wave-to-hit-uk-as-platf...