Supply is one part, being able to repair is another. The tiger was a massive pain in the dick to fix. It had a weak gearbox that took _hours_ to get to.
Plus most of the parts were bespoke, which means lots more tooling needed to service everything. The other thing is that germany wasn't actually that mechanised compared to the french, or english
Which is exactly the topic under discussion.
In today's world, the US outspends the next 10 countries combined. In normal times, it values the lives of its servicemen, and is willing to spend quite a bit to ensure dominance. So it will often have boutique gear that other countries could never afford.
The US outspends the next 10 countries combined in peace times. By comparison, Germany outspent the US on its military by a factor of 20 on the eve of WW2. Obviously once the war got going, the US' immense industrial capacity (along with the other Allies; the British Empire and the Soviet Union had the number 2 and 3 GDPs) was unstoppable.
We no longer live in the age where the US represents half of the world GDP and the bulk of that is manufacturing. China's has a larger economy in terms of Purchasing Power Parity, it has extensive manufacturing capacity, and a vast population. If push came to shove, we wouldn't be able to simply outspend them. In that hypothetical conflict we are the germany with a bunch of questionably useful wunderwaffe.