Even including your towns the vast majority of houses have off street parking, at least according the the rac
You have a very niche issue.
1) storing car on public land at home and office
2) driving excessively long mileage each day
3) having a small capacity car
This is a tiny number of people.
That's still leaves millions (?) of households with on street parking.
Most commuters outside cities get on quite ok with normal cars - because they have to - and a third of them is hardly "niche".
You’re combining. My mother doesn’t have off street parking as she lives in a town. She’s one of the 30%
If she had a typical ev she’d have to charge it once a month.
You’re talking the 30% without off street parking and have high mileage (same needing more than one charge a week).
You can probably get away with that in most cases with on-street parking with a mix of commercial chargers and work if you're lucky.
That "probably" is the point. Your average normal car user (especially in financially challenged times) fighting for a car space on their street is not motivated to take on that higher risk at higher cost in a less competitive market to keep the equivalent of HN demographics happy.