You’re right, being poor is expensive, but that doesn’t really apply to charging a vehicle.
The term “being poor is expensive” is generally applied to situations where you don’t have the money to pay for something upfront (a quality product, bulk purchases, preventative maintenance, preventative healthcare, down payment on a house) so you have to spend smaller amounts of money repeatedly and/or have a large unavoidable cost as a result (multiple cheap products that wear out, multiple small purchases with a higher per unit price, a blown engine, a root canal, rent), which can cost a lot more over time.
The electric bill is post-paid, not up front. Not being able to set aside the “$10 every few days” to pay the higher bill at the end of the month with money left over is just poor money management.
That being said, the higher purchase cost of electric vehicles preventing poor people from taking advantage of lower operating costs that would more than offset the higher purchase price after some number of years is an example of it being expensive to be poor.
My grandparents house built just after ww2 had, what was for a long time, a standard two car garage. Enough room for two land yachts from the 70s, lawn care implements and various other stuff and you could still open the car doors all the way and walk around. My parents’ house built in the 70s was the same. It’s more recent construction in built up areas where they are shrinking. They’ve been getting smaller as developers try to cram more liveable sqft on smaller amounts of land.