Why does nobody warn you about a $60 laser level that lies to you?

I picked up a cheap $60 laser level at a pawn shop in Fresno to frame a closet and it read dead level on the floor but the header came out 3/8 inch off over 6 feet. I only caught it when my 4 foot Stabila showed a gap I couldn't explain, then I checked the laser against a water level on the driveway and it was drifting the whole time. That little screen made me trust it, and I hung two doors before I figured out the wall was a trapezoid. Now it lives in the junk drawer and I'm back to a chalk line and a plumb bob like my old boss told me. Anyone got a sub $150 laser that actually holds true after a drop? I don't want to gamble on another one.