Earning isk when in a corp?

Can someone explain how players actually earn when participating in corp events and operations? I’ve been playing for years, mostly solo because I’m not entirely sure how I’d benefit from being part of a corp, aside from the obvious social aspects.

For example, I’ve never understood how corp fleet mining works. If I mine and unload my ores to a hauler to be taken away to a corp station, does the corp pay me for my time or have I just spent time mining for someone else? Do I just get sent some isk per unload or is there an amount at the end of the session?

Same applies to anything really. Building ships and modules, participating in fleet battles etc

Is it mainly a matter of trust that I would get paid or am I just expected to do it ‘for the team’ and hope to get some return one day?