The DMCA is the least of your worries. The EPA has figured out that the only only reason people actually want to update software on their tractors is to turn off emissions controls.
All of this decrease the useful lifetime of equipment.
And no, all of this is not required, a trucked was able to pass California regulations with an old pre-EPA-regulations diesel engine, but the tolerances are a lot tighter (ie. forget about that chinesium oil pump with a couple thousands too much shaft end play), maintenance is a lot trickier...