Didn't see your edit there.
This is something I've been ranting about for ages too.
The EU doing it would be a good start, but all batteries should really have an ISO standard.
If you've ever watched some of the teardown videos on Youtube, there are actual technical differences but an ISO standard should sort that.
I watched some teardowns for Lidl's Parkside 20V and Aldi's Ferrex 20V/40V battery packs (because they are cheap if I ever were to get around to trying an ebike conversion kit - the Aldi with its "40V" (really 37V I would imagine) should fit most 37V ebike kits).
The biggest differences is whether the "don't discharge below the damage threshold" is on the tool or the battery.
Other differences are to do with the controller and balancing. Think Parkside recently changed theirs to be balanced (so in a pack of 5 x 3.7V, one cell being too low is less likely to damage the whole pack).
But as I said, all of this could and should be part of any standard.
As for IP67/68 and removable batteries: my old Samsung Galaxy S5 was IP67 and had a removable battery. As did my earlier Motorola Defy+. There really is no excuse.
The recent trend of the battery being sandwiched between the screen and the mainboard (I'm thinking of a Nokia 8 teardown I saw) is complete nonsense has very little technical reason aside from maybe the shock horror 1mm of extra thickness. But even screwed down like (AFAIR) Moto G5 is fine; it's the glued into the middle which isn't.