While regulations vary, I am not aware of any utility under regulations that would allow them to penalize a customer based on what they are plugging in. Nor can I imagine a scenario under which a utility would want to. (They may indeed charge more for high or peak electricity use because both of those affect utility costs, but that has nothing to do with whether that electricity goes in to an EV or not. Such a rate would apply to all customers, not just EV owners).
Every utility I've ever talked to loves the extra sales and stickiness (and, generally, willingness to try new models) of EV owners. Off-peak charging allows for more income without capex - better utilization of their existing capital, which means lower costs. A more steady load also makes it easier to integrate intermittent renewables. Utilties offer encouragement (like lower rates - off-peak, of course - or EVSE subsidies) when they are allowed to (which more and more they are being allowed to, because encouraging EVs lowers costs for all customers). If their regulators don't allow that (they don't by default, so most places with few EVs haven't changed regulations yet), at least they can use their knowledge of EV locations for capacity and transformer upgrade planning to provide better service at the lowest cost for all their customers.
An EV is a very significant addition to the electric load at most homes, and it really helps utilities (and by extension their customers) if they know how and where their loads are changing. Planned change is smoother and cheaper than reactive change.