In car industry there's a multitude of highly specialised "tuning services" that tailor a "generic" car strictly to your needs. The manufacturers themselves handle this too, but only on special basis, for special customers - bulletproof glass, titanium hull, all that extra custom stuff, for top 0.01% customers, and expensive like the hell too.
In commercial software it's much more rare, possibly because the "single custom unit of software",due to development cost not being split amongst thousands of customers would be extremely expensive, and also tinkering with an existing car by a third party company is so much easier than working with compiled binaries without access to sources, and few software giants would risk passing their sources to third parties even with strict non-disclosure agreement. (actually, that's how NT4 and W2k sources leaked, they were stolen from servers of a third party company working on a UNIX-Windows interoperablity toolkit for MS.)


Yes. Except possible != profitable. In most cases providing 100% of this service "bundled as standard" with the program would cause so much overhead "support cost" that it simply kill your business. Providing API allowing for more seamless integration of your software with some larger systems, than ctrl-c ctrl-v between two windows of different systems would solve a lot of problems, though obviously not all. And providing the support for a fee... well, IBM and some other giants went so far this way, that they gave up on profit from the software itself completely. And I suppose the customers will prefer to hear "Yes, this can be done, but this will cost you" than "no, it can't be done".