Lobby the government for providing basic guarantees for ease of access in digital environment. Some political factions like the Pirate Party in EU is already working on acts like Digital Fairness Act to prevent such monopolies.

You can have (or provide) a phone that's specifically for those use cases and you can turn it off for actual communication.

Don't give your money to these places? HSBC won't let me use my rooted phone either, so guess who lost my business?

Boycott.

Lawsuit.

Organise.

Publicise.

Shame.

Stop buying their tickets.

The solution is to not buy the tickets

The solution is to quit frequenting places that abuse you like this.

But it seems you LIKE being abused.