Two standard sizes, big and small. Sorted!
But, for the same reason that not two cars have the same water pump, oil pump, disk brake rotors, alternator, wheel no. of bores and spacing, etc. etc., I reckon it's not going to happen anytime soon.
In fact, a lot of cars do have many of those things.
Not so much as back in the day, though, when many Brit cars had parts which were interchangeable, not only between different brands from the same parent company, but between totally different companies.
The USA were similar, & in Oz, it was hard to tell the difference between starters & alternators used by Holden, Ford, Chrysler, & even Renault.
My "Australianised" Renault R12 also used the same distributor contacts as a Holden------very convenient!
The crankshaft bearing shell kit for my Leyland P76 was marked "GM or similar".
a cheap EV battery swap design could work like this.
designed to fit under a front wheel drive electric vehicle between the rear wheels. the rear bumper bar would swing up in theory, for access.
like a flat filing cabinet drawer, allowing complete battery drawer access by way of a type of modified pallet jack.
no raised level platform needed, different battery capacitys could be used on the same EV.
so in theory it be possible to battery swap at home. a raised level automated platform can do the same job.
as a manual battery swap. you have a choice with this EV design.
here is what I think about how a pallet jack battery swap EV design would look like. see abstract image
small auxiliary battery remains in the EV to run the automatic coupler from the vehicle side.
plug in the battery without touching high voltage connectors.
see how electric bus line automatic couplers are used on railways.
do you think this will work? or is a better battery swap design.