If 50% of non-apartment households got an EV, that would be ~33% of all households with an EV. With your definition of 30% == "pretty mainstream", it is pretty

If 50% of non-apartment households got an EV, that would be ~33% of all households with an EV. With your definition of 30% == "pretty mainstream", it is pretty achievable to have EVs be mainstream while excluding every apartment dwelling household. Roughly 8% of US households have zero cars. What do you imagine the breakdown is between apartment and single-family households? I'd guess probably all dense apartment, the main cohort we're talking about that would lack charging access. So for those actually looking to charge a car, if 50% of single family homes moved to an EV that would in reality be even more than just ~33% of the market, because 8 of the 35% of apartment dwellers weren't shopping for a car to begin with. It is really more like 27% of households want a car and live in an apartment that would be challenging to charge a car in. But hey unless we solve it for 27% of the population it just can't possibly be considered "mainstream".