As opposed to the allied light vehicle rush?
Allies have weapon racks (bazooka/piat), t2 ATG (brits/Sov.), early mines etc etc etc.
There's lots of options, you don't have to neuter your build by preemptively building double AT guns or shit like that. Scouting your opponent can also help a ton, you don't need to divine the luchs you just need to check if he's got a medic truck or a mech truck.
The difference is germans have learned how to deal with light vehicles, while allies have apparently not given how many people don't know they can build bazookas/PIATs.
Who is going to build 2 ATguns to counter a Luchs? What the point going to extreme silly builds to denature my words.
In the fast Luchs, the problem isn't the Luchs alone but the all around. Shreck+flamnade+numeros volks+Kubel+Sturms (for no fuel cost) and the Luchs.
Before facing the Luchs you need to face a powerful OKW early game, and to face it, you must invest in tools. The game isn't balanced around USF or Sov being able to defeat early OKW just by spamming Cons or RM, even more since Volks and Sturm has been buffed and Kubel turned into a super fast harass unit. So you must invest in fuel tools, like early light vehicle or suppression or healing, grenades etc...
The problem comes to the Luchs because what you invested to counter OKW early is naturally countered and wiped by the Luch.
This is why people, like me, want side tech for OKW, or whatever mp/fuel sink for OKW early game. If as OKW you want a powerful early game, you invest on it and delay your midgame. If you want a fast Luch, your early game will not be so powerful.
As USF, if I want a fast M15, I don't have nade/heal/BARs/Zooks, my early game is weaker
As Sov, same happens if I want an early T70