I would rather have a £10,000 interest free loan over 4 years to buy a used car, than pay finance charges to a bank/or under pcp/ hp etc.
New anything is of course a depreciation nightmare, and as soon as you get the keys, you are in "the cars worth less than you paid for it"/finance-outstanding territory, ICE or Electric. When depreciation is wrapped up in the "per month" calculations it is hidden from view, but you are paying for it
On the used EV front, even if my current leaf depreciates to zero in 4 years, so far I am well on course for having over £5,000 in fuel savings in hand doing over 12,000 miles a year. So if the car is worth nothing at the end of 4 years, 100% depreciation, ownership would have cost me £5,000 over 4 years.....£104/month. Fairly bargain basement even at those calculations.
If I was thinking about buying an electric car in Scotland, I would certainly look at picking up an interest free loan if its available.