Some remarks basing on my experience with Kion/Linde.

Linde developed a customer version of diagnostic software which is destined for key account customers.
The cost was extreme - in 2008 basic soft costed something between 4 and 5 k euro, plus yearly licence (over 1500 Euro).
The soft had only basic features (no adjustments, only diagnostics), but it enabled at least some orientation about trucks condition.

This was presumed for REALLY big customers and the agreement was usually signed between HQ guys from both sides.
I remember the deal with Kaufland when tousands of trucks were delivered every year for several years all over the Europe.
And this deal included the access to the software in several countries. At the end , at least in Poland, the soft was never delivered.
Theoretically, it's up to the dealer which of the customers deserves the access, but praxis is rather tough.

Anyway - my opinion is, that within 5 - 8 years, the manufacturers, who sell the sophisticated trucks, which need the restricted access software to maintain them, will encounter the same problem as Microsoft in Europe, with their Explorer or Media Player attached to Windows.