With the current engine, the only way a real-time map can be done is to fully remake the map on 1:1 scale. This is practically impossible with the scope of a (one day) full continental US map.

A bit of background: the map is scaled. For the ATS map, this is 1:20. When you drive time passes 20 times as fast as it does in real life, so an hour on the road takes 3 minutes of real-time: the road is 20 times shorter than it is in reality but so is the time you need to drive over it.
Inside cities and major truck stops the time scale is different, depending on the place in question. Usually, it has around a 3x time scale, compared to the countryside's 20. So time passes slower inside cities, but still faster than in real life.

Say you want to change this, then you need to make the entire map a 1:1 scale, meaning every mile in reality is represented by one mile in game. This would require remaking the entire map!
ATS has already gone through a redesig. When it came out the scale was 1:35 but this was very unsatisfying and they remade California completely. You can find info on this on the blog: https://blog.scssoft.com/2016/06/the-rescale.html

It is possible a modder will create a 1:1 map for ATS, but then you can at most expect a single city plus surroundings because of the immense amount of work required. For ETS2 there were a few 1:1 map mod projects but they all fizzled out because it takes so much time to map every single stretch of a road or city.

I've seen the game being compared to FSX and Farming Simulator which do not use the same kind of time compression, why can they do it?
FSX doesn't need to represent roads, it just needs to have clouds and a passable landscape. Only the airports are drawn to scale.
Farming Simulator can afford to be (close to) 1:1 since it is only a single farm and surroundings.
Neither game is comparable to one where you drive across half a continent.