It's not unusual to see bees nosing around on the surface of the soil. I'm not sure if anyone knows for sure what their reward is.....minerals (soluble salts), moisture, who knows?

During a dry spell recently, there were bees on a wetted local drinking fountain, more typically the hangout of wasps later in the year.

I had just recently added water retaining crystals to the basket, I wonder if that has anything to do with it. It looks like they are digging in the dirt.
They are quite friendly, I deadhead my petunia every night and they don't care that I'm there.
I wonder if they might be hover flies?
They also kind of crawl around on each other, mating behaviour I wonder?

Those are honeybees

Honeybees typically ignore anyone or anything messing around near them when they are on the job.

They are even stubborn to leave the public drinking fountain here that is frequently used.

I like it that they are honeybees but what were they doing?

Have now seen a honeybee with its head down a fountain spigot; when I pushed the button he flew off. At a another distant fountain, multiple honeybees on the damp concrete base.