Plenty of petrol stations have EV charging points but they're horrendously expensive. EV running costs are only cheap if you can access domestic electricity rates or take advantage of cheaper off peak tariffs. Chargers out on the network re usually fast chargers which is not good to use regularly or routinely as they degrade batteries more quickly. Some EV's battery health can be degraded as much as 20% after only a few years of use if fast chargers are used routinely, and nobody is going to invest in slow chargers out on the network.
Also if you're the owner of a petrol station why would you invest in installing a couple of chargers...with the available space you have you can probably only install a couple of chargers and therefore will earn a pittance from them probably never paying back the cost of your investment. Why bother when you can just continue raking in your income from selling petrol and diesel and being a small mini-market to the local community? The economics just don't stack up. The only way the economics of EV chargers can stack up is to have lots of stalls so you can get the throughput of customers and that takes up acres of ever more expensive land and real estate. One petrol pump can service 10 or so cars per hour at the average cost of about £50 - £80 revenue per car but one charger can only service probably only one or two EV's per hour maybe raking in £20 - £50 per car. And one car park space can enable many cars per hour to park up while people pop in to the mini-market if they're not stopping for fuel, so if you lose those car park spaces to EV charing stalls then you disincentivise people from coming to your mini-market, which I suspect is now how most petrol stations make their money.
It seems obvious to say 'just put ev chargers of every street corner and that will solve the problem' but who's going to pay.
And having spent a fair few hours at EV charging stations up and down the country myself I can guarantee that most people sit in their cars while they are charging and are not spending in the shops every time - they may pop in to use the bathroom facilities thereby costing the owners more money in water, toilet paper etc. That is why some places that have EV chargers, like hotels, are now starting to charge parking fees for EV drivers to park up to use the EV chargers precisely because its costing them money.