The friggin device probably costs over $100,000 and comes with a full-time support contract. They could add an extra $500 worth of CPU and RAM to the device, assuming they can find a competent evil kernel dev to do the work
You'll find that dollars don't actually override physics. If you can't cool your extra fasty CPU, it's not going to be vey fasty.
For reference look at panasonic's "fully rugged" toughbooks. A baseline 31 will cost you $3700 for a 7300U, 16GB RAM, a 256GB SSD, and a 13.1 1024x768 display. On base spec it'd be a $800 laptop if you could find one with a screen that bad, and that outdated a CPU.
Except you can drop the 31 from 6ft, you can literally hose it down, you can rub it in a dirt pit, you can drive on it with a truck, and it's expected to survive and work fine. It also has a baseline 20h battery. That resistance, that ruggedness, comes with limitations. And it's not very useful to have an indestructible laptop if a gentle shake kills the electronics either.
Hence "thermal and reliability concerns". You look for parts you can cool with a relatively low thermal budget — which limits your performances — and you look for parts which have been designed and manufactured for industrial resistances, which also limits your performances. No matter how you slice it, a GTK Boxer won't outrace a Bugatti Chiron.
The parent comment means that hardware that runs in a rugged container thingy is typically limited by thermal constraints. It's not the $ 500 that's the problem, but a faster CPU could overheat with that packaging.
