If you hold tuning and scale length constant, then the string's tension is determined by the weight of the string. You can change the weight of the string by changing the thickness (gauge), construction (roundwound, flatwound, plain wire), or material. This is true on both acoustic and electric guitar, so the premise of the question is not quite right- we could have roundwound and flatwound electric guitar strings which both have the same gauge but different tension. You could also have a set of nickel wound strings and steel wound strings with the same construction, but again have different tensions, because the nickel strings will be heavier.
Acoustic guitar strings can have more difference in tension within the same gauge, however, because there are more materials which a string could be made out of. Electric guitar strings have to be made out of ferromagnetic metal (or else they won't work with electric pickups). Acoustic guitars can use nylon or gut, which is far lighter than steel or nickel.
So, why are electric guitar strings sold by gauge? It would make sense to sell strings by tension, but tension depends on the end user's tuning and scale length. And actually, these strings are sold by tension, in a way- nearly every set will say "light", "medium", or something similar on the packaging. But these are just the manufacturer's opinions, so guitarists look for gauge instead.
Overall, gauge is a fairly good indicator of an electric guitar string's tension. They're all made out of ferromagnetic metals, and they are generally roundwound for large strings and plain for small strings. Because of this. the variance of tension between two sets of 48's will be fairly small, and the guitarists that care about this difference will just try a few sets of strings and find their favorite.
And lastly, we have to ask, why do we want "slinky" strings with higher tension? The easiest way to get higher tension is to use a thicker, heavier string. There are some guitarists that hate the feel of a thick string under their fingers, but the easiest solution is just for them to get used to it, rather than engineering a string that feels like something it's not. The other, more important issue is that thicker strings are generally stiffer, which is generally bad for a few reasons (mostly, it sounds a bit worse). This is a problem that engineers do work on- that's the whole reason we have wound strings in the first place! If stiffness wasn't a concern, we'd have every string be a plain string.