Do most YC companies follow this balanced approach?
For example, if you're doing a land-grab in a newly discovered market, such as Uber, you have to prioritize growth above all.
On the other hand, if your market is well-established and your plan to win by superior polish of your offering, you're better off growing slowly, using revenue both as a funding source and as a guide for making a superior product.
In any case, the competitive situation will dictate if you have to grow fast at all costs (by raising large rounds), or if you can grow slowly by using your own revenue.
Side question: why do the new regulations have to be similar to the current taxi system? Uber doesn't need eg a medallion system, they'd be happy with onerous legal (eg reporting) requirements to keep upstarts out.
The new system does not need to the same as the current medallion system, but unless the new system is providing them with a competitive a means of keeping upstarts out the market will become one of perfect competition where profits all end up with the consumer.