These are some beautiful skid marks. I like the smoke/dust as well. Really the physics/damage were pretty good for a game of that generation.
Beam's skid-marks aren't horrible actually, it shows quite well not all skid marks are just dark black lines and are more often than not quite faded, especially on the road tires most cars use. That being said they could use some texturing in terms of thin normal maps, as well as some sharpening since they currently have the appearance of using a black brush in any graphical editing software. As already mentioned this is alpha, so I would not be surprised if some improvements are eventually made.
Have you observed how with ABS you can see from skidmarks how ABS did work out? Pressure and slide percentage affects skidmarks quite nicely, you don't get that with all games, with many you have much less in terms of dynamics to skidmarks. I would think that way skidmarks are done is much more solid than most games. Sometimes you get barely visible skidmarks, but drive that corner many times and you start to see what is great in this method. I think that skidmark buffer could be higher though, however that might be again performance problem if too high. If from road texture bumpmap you could get information about surface so that holes on tarmac would not get black stuff so easily, now that would improve skidmarks a lot and you would need another computer to render those skidmarks, but it would look so much more like in reality. With current technology we are limited on driving smooth surfaces, tarmac is not coarse, it is still more like surface of glass, even some improvements have been made, visual micro and macro texture of tarmac surface are probably not going to happen in next 10 years, you would need that to get really realistic skidmarks. That said, you can have some of it in BeamNG, perhaps unintentionally, some meshroads of addon maps have something called washboard on tight turns, powerslide there and you can see how well done skidmarks are in BeamNG, it is not straight line like a ruler on top of road surface, it is so much better, skidmarks appear to be on road surface. What might need bit of adjusting is minimum velocity required to leave skidmarks, but that again might be set so because of performance issues, for example in real world, when semi turns tightly, it leaves skidmarks on ground, it is not going fast, there is not lot of sliding, but rubber is left to road surface because of road surface being like rough sandpaper adhesion, abrasion, all kind of scientific things are related to that. With little tweaking it could be bit better without needing to wait 10+ years to get proper simulation of the effects involved, but only if performance allows. I don't know how heavy performance hit it would be to have 20km of skidmarks?
So, your asking wether the skid marks from a 2003 video game that can be found at the back of the arcade in my local bowling alley, are comparable, if not, better than the ones in BeamNG? Well, it's not that easy, to make it short, yes, they are comparable, as, really, both are black lines generated from the increased detected tire frictions hitting the ground, really, any real good-poly game with cars can have good skid marks, as they seem rather basic as in their look, but getting it right so that they look like they are coming off the tires is the hard part, and both games do that well