Do you think that a company like Intel for example will pay it's Californian workers the same as workers in Israel or elsewhere?
But workers in California do their work there, as do those in Israel. The difference is that pilots, by their nature, can be based in one place yet asked to operate elsewhere. Unless there is a clear agreement that they cannot use pilots from a cheap base do do the work of pilots from a base with better T&C's then that is what any management will eventually strive to do. You will find crew being positioned about to achieve minimum cost levels. You may find that eventually most shorthaul crews are based elsewhere and only long-haul crews who are duty limited based on full T&C's.
There is little new under the sun, BA introduced cheap bases in MAN and LGW but it was agreed and understood by both sides that if a MAN crew ever operated MAN-LHR then all hell would break loose.