Back when I was a defense contractor, our equipment all had to calibrated by the Navy cal lab. One of my co-workers was very proud of his new Fluke 87, I opted for another brand with all of the same features, but only about $55 instead of the nearly $300 he paid for his. We sent them in to cal and mine returned cal'd, his was returned as "Defective - Uncal" and he was forbidden to use it on the job until it was repaired or replaced.
He sent it back to Fluke (on his dime) and they repaired it and sent it back, it passed cal that time. I never missed a chance to ask him if his meter was in cal and should we use my cheap $55 meter, since it passed cal the first time. LOL
All of this is to say that just because Fluke is expensive, it doesn't mean they are accurate right out of the box - only a cal lab can do it and they are NOT calibrated by Fluke, even for those exorbitant prices. Anything can be defective, price is never a guarantee of anything except nice profit margins.
For RV use, most of the time a test light will do what you need, it's not like you're doing power supply alignments on a $65,000 power supply and aligning everything to .00v under load. The cheap HF meters will work ok to let you know if your battery charger is/isn't working, and I usually just give them to whomever I'm helping out at the time. Chances are, that's why I'm helping him out, he didn't have a meter.