I am not a flooring expert or installer but I can give you an
perspective as a design engineer.

The joint have a tongue and grove that must mate up. There has to be
clearance between the tongue and grove to allow the parts to go
together. This will result in one board being able to above its mating
board by the amount of the clearance gap I would expect the clearance
gap to be at least .010 inches. Also the board thickness has a
tolerance (say +/- .005, more likely +/- .010). Now consider each
board expands and contracts at a slight different rate. It is wood
after all. A lip of .005-.015" sounds very reasonable. If the floor
was perfectly flat (polished glass or metal held to precision
tolerances) then a flat floor with no lips greater than .01 might be
possible (this accounts for board thickness tolerance and expnsion/
contraction rates). So how flat is your sub-floor?

Bottom line: The installer came out and inspected the floor. Maybe his
attitude wasn't the best. A manufacturer rep is coming out to inspect
the floor. It sounds like the installer is standing behind his work.
However, to be honest, you do not have reasonable expectations. If you
want a floor where you would not detect the slight lippage, you should
have gotten a floor with micro beveled edges.

Just my opinion.