First, you have to manuelly level it with the bubbles, so there goes the perceived "accuracy" of a laser tool. For a laser tool to give you any decent accuracy it must be self levelling, which uses an internal pendulum and gravity. Same theory as a plumb bob.
Second look at its claimed accuracy rating, 1/8" in thirty feet. You could get better than that with a quality 24" level. And that accuracy is based on perfect conditions in the testing lab, where I gaurantee you they don't level it with those cheap bubbles before the certification testing.