Why it's not widespread?
A grooved surface can only act as drainage if it is installed at an angle. And a sloping bartop might not be that popular with patrons!
If it's not at a suitable angle it will act to collect the water and just allow it to sit there, also extremely unpopular with patrons I would guess, plus it would make it much harder to wipe condensation or spilled drinks up when the inevitable happens.
On top of all that think of the potential for that profile to trap dirt. A health inspector would probably take one look at it and 'ask' for it to be replaced.
How should it be covered and treated?
If you decide to go ahead with this material anyway I think there are really only two good options and that is epoxy or fibreglass. Both applied thickly enough to fill the grooving completely :-)