I have four "good" dial-type tire gauges (two of which came with calibration certificates), a compressor inflation adapter with a calibrated gauge, and an Autel MaxiTPMS TS501 scanner, and no two of them read the same pressure on any tire. I just checked my wife's Prius' tires, and her left front read 34psi, 35psi, 36psi, 37psi, 39psi, and 41psi (the Autel TPMS scanner reading).
I get that accuracy within a pound or two might be too much to expect, but 7psi difference between the lowest and highest readings is ridiculous.
I'd order another calibrated gauge and throw the others out if I knew it would be accurate, but I have no confidence in the calibration certificates at this point.
Ok, rant over...