Basically, since the advent of bebop, the overwhelming majority of pianists use sparse comping. This means that they don't really provide bass, they just provide shell/rootless chords for themselves to play, the main focus is soloing in the right hand, or when others solo, just providing chords in pulses. The actual bass is provided by a double bass player, who plays a bassline.

Before that, the prevalent comping style in the left hand was stride, which provides a rich bass backing. (You know, the oom-pah stuff) Contrary to the common criticism, if coordinated well, this can also work in the presence of a double bass player (just check out Fats Waller recordings, many of his Rhythm recordings had a double bass player!)