Shouldn't all crypto be backed by bitcoin ?
Nope! That will limit the innovation in crypto market and also make useless coins pricey for no reason. Gold reserve was abolished long long ago because it doesn't make sense! Similarly bitcoin standard in crypto market doesn't make sense!
How could a "Bitcoin Standard" emerge? For example, if you could pay for food service etc everywhere with bitcoin, would that be enough to essentially drive bitcoin as a backing standard ?
Again no! Bitcoin is valuable because it is the pioneering cryptocurrency. People have already invested millions of dollars into mining infrastructure around the world. That's how bitcoin derive value. Paying bitcoin for food or regular item is not a parameter to drive its price or its position as a standard.