at least 5km is the range of those ATGM and if you look at the map you post at least the part is shown you see Russia have the same amount of roads , so its not important if they are on offence or defence . the important part is do you have enough battlefield awareness , to know when the supply comes and where they go and target them or not . the situation would have been the same if Russia was on defense and Ukraine on offense
First of all, ATGM can shoot 5KM does not mean you can hit anything with it 5 KM away. You are lucky if you hit something 2 KM away, 5KM you will need visual enhancement.
Second of all, the entrant of those ASR is at least 10+ KM away, and the diverging point is probably twice as long, you can't hit it unless you position your artillery in the area, but then once you do, YOU WILL BE COUNTBAT. So do it with your own accord.
And thirdly, again, it's NOT ABOUT Battlefield awareness, this is different because in Ukraine, Supplies, not just at the immediate area, but the entire battlefield. For Russia, the point of origin of your supply is Russia, which mean there are only certain road you can take to divert it into Ukraine and feed your troop in Ukraine, for example, you won't be taking a road north of Moscow to have your supply going into Ukraine, it HAS TO BE SOUTH AND SOUTH EAST., that would dictate a lot of flow and movement because they are all originated at the same point of entry, I mean you don't go loop around into Belarus now when Ukraine took Kupiansk, or South into Black sea because Ukraine took Kherson, that mean there are only 2 ways Russia can supply their troop in Ukraine. Either North thru P-66, or East thru E-58 from Rostov. P-66 is under Ukrainian interdiction now as they push close to Kreminna, which mean technically only E-58 is open, (I mean you can try run your supply up north thru P-66, that's probably mean suicide) which mean you know where the direction of supply is going filter thru from Russian line, which mean you can interdict those area. Either with HIMARS or Direct Action like Kerch bridge.
For Ukraine, supply can and WILL come from all the area in Ukraine, it will be coming from Kharkiv, it will be coming from Dnipro, it will be coming from Lviv, Kyiv or any direction that is not facing the Russian. Which mean for the Russian, you need to know where or when the supply is coming thru, and more importantly have the ability to hit them all. That mean can Russia hit every major MSR in country? Bakhmut is a small city, it's a small example, yet you have 6 road leading into and out. On the other hand, there are only 2 roads leading into and out of Soledar and Bakhmutsky. And the main supply route is filtered to the South. UKRAINE WILL KNOW WHERE THE SUPPLY COMING FROM. That's the different.