I would NEVER shave my labs.
I have seen people with shaved labs...it ruins their undercoats and they look absolutely ridiculous.
Their coats/undercoats serve a purpose.
Now, a good friend of mine did shave their Lab down - they have two Labs and live out in the country, so the dogs run wild all day. It was summer and, being Labs, they were swimming in the creek, pool, and horse trough on and off all day, every day. Winnie's undercoat started to get moldy.
So they shaved her down. It grew back just fine and I don't think they've had an issue with it again, but there for awhile it was just nasty.
But yes, typically I think people who shave short haired dogs are idiots. We had someone bring their broken coat JRT and a Min Pin in for grooms...they wanted the JRT
and the Min Pin shaved. Yes. The Min Pin shaved. They hardly have hair to begin with, I don't know why in the heck they wanted to shave it.