Are alternative roofing types, such as rubber roll, usable for a typical residential sloped roof?
I think one could feasibly cover a sloped roof with that stuff, but it would be very odd.  Most HOAs and neighborhood associations would reject it.  You neighbors would be annoyed.  If snow or ice accumulations are possible for the climate, it probably would cause random ice sheet falls, which is not an issue for its intended use on level roofing.

As some comments hint, a properly installed composite roof becomes a single, seamless sheet of roofing.  It only takes one warm day for the shingles to soften and then seal together.  Even before self-sealing, the shingle and seam overlap makes the roof rainproof.

Anyway, the danger of a roof leaking is not the integrity of the initial installation's seams and whatnot.  It is the decades of abuse wrought by the weather (sun, hail, wind, snow), moss, leaves, tree branches, animals pecking or running, maintenance people walking across it, using shovels, picks, rakes, and brooms to clean it, blasting it with a power washer, etc.  Any of those can poke holes, cut slits, move flashing, or lift up edges.  That's the most likely cause of leaks.