Generally, when you see a weird problem like this, you cannot look at it in isolation. You need to look at the whole circuit, or at the very least the first stops upstream and downstream from there.
Normally cables are used, and cables come in standard colors (black-white or black-white-red), and concessions are made to deal with that very serious limitation. However, wires have coarse color codes.
- Green, green/yellow or bare for ground. If conduit is involved (this looks a bit like conduit), and the conduit is metal, ground wires are not required because the conduit metal is an acceptable ground.
- White or gray for neutrals - in cables, white can be re-marked to be a hot if needed, and this marking is usually forgotten. In conduit, you're supposed to use the correct color wire, unless it's a cable in conduit.
- Any other color for hots.
I suspect your wiring may be done either with conduit or metal-jacketed cable, where the metal is providing the ground. That is normal and healthy, and you don't need to give grounds any more attention.
When you see 2 black wires on a receptacle but only one white, look for a nearby pigtail where 2 whites get joined to a pigtail. I see that in this box.
Putting 2 wires on a receptacle (with the receptacle tab not broken) is simply an alternate way to do a pigtail splice. The methods are equivalent.
Why would the whites be pigtailed but not the blacks? Possibly this is a multi-wire branch circuit where neutral is shared; neutrals are required to be pigtailed so removing a device doesn't break neutral for the other half-circuit. If it's like that, keep it that way.
The one other thing I would say about grounds is that if the metal "yoke" of the receptacle (that the mounting screws go through) doesn't make hard clean metal contact with the steel box, then current Code requires you run a green or bare ground wire from the receptacle's ground screw to the grounding screw on the receptacle. That will be a #10-32 tapped hole in the back of the receptacle; you can see it in your photos, it's the somewhat smaller hole.
They sell green ground screws (with or without pre-attached pigtails) at the building supply. You don't need to use green ones, but it has panache.