If the screw mountings are not the same, then it's not a direct or drop-in replacement. The Gibson and Epiphone pickups not only have different mounting arrangements, they are different sizes. They are different pickups. The only thing they have in common is the shape of the bass they come out of (and the parent company, I suppose). If people want replacement pickups, they usually want something they can just plug right in.Two or three screw holes - does it matter?
The screws screw into the body wood of the pickup cavity - no one will ever notice the difference...
Obviously, people are entitled to like whatever they like. If someone has an Epi T-bird with Epi pickups and they want the look of a Gibson T-bird, more power to 'em. But there's quite a bit more involved in making that particular switch than unscrewing & removing a pickup, then screwing in and rewiring the new pickup. And it's disingenuous to say or imply there's no difference in the process.