I know, I just don't see the arbitrage in what's described? If I order online because it's cheaper than the high street, that's not an arbitrage – the arbitrage would include then selling it on the high street afterwards, getting paid to close the gap until it reflects only delivery fees and the value of immediacy.
And to make that an arbitrage you'd need to subcontract someone local to do the job you've taken the California pay for. It doesn't mean 'get a better deal in a non-obvious way/place', it's taking both sides of the trade in different markets.
Good point about the project lifecycle. In my experience, open source contributions often get repurposed this way. The key is clear licensing from the start.