if bee hives have any parts that need to slide or disconnect, latex paint has a condition called "blocking". What that is, latex painted parts will tend to stick to themselves. Supposedly "high end" latex will not do this, but I know the stuff from the big box stores is awful for sticking.
Our first hives were Top Bar Hives, and being as clueless as I am about power tools, I nicely painted the kits inside and out with Behr top quality interior/exterior latex, thinking it durable, quality, yadda yadda yadda. Including the inside and outside of the lid. The lid, of course, stuck to the hive.
Baby powder did the trick. After a season, the paint had dried/cured/aged enough that there is no longer any stick.
Spar varnish, or urethane is one of the prettier finishes, but only has a hive life of about 2-3 years, and unlike paint, needs to be sanded before recoating. I'm too lazy to sand just to repaint...Just like I hate scraping because of the mess.
Generally, I like 2-3 coats of thick paint, with 3-4 days drying/curing time. But the hives can't be so callously abused. Not if I want them to last more than a few years.
A well maintained hive box can last up to 20 years, if properly prepared...Hence 3-4 coats Tung oil, and then 4-6 layers of Johnsons. Curing time alone is going to be about 44 days.