Plenty of places just assume you can do on-call or it's required, including high-tech companies. I'm not compensated outside of normal salary/equity for on-call

Plenty of places just assume you can do on-call or it's required, including high-tech companies. I'm not compensated outside of normal salary/equity for on-call hours. If I don't get paged, great. But if it's a heavy week I don't get anything extra. I'd love to join a union to be able to reasonably bargain against this.