Tesla can seemingly issue new shares and the public market just buy them all up at a huge valuation; I think that's what is meant by "unlimited resources".

There's tons of places with effectively unlimited money. But very few places that have nearly unlimited resources. Some key resources are usually inversely correlated with money: decision-making latency and throughput, clear focus, and iteration speed. That's because money buys headcount, not good leadership.

Do you think sls development is less than what spacex is spending on starship?

I wouldn’t be surprised if Apple has produced many times more iPhones by weight than Tesla has produced cars