Sure you can be self taught in plumbing. Overall we are just much less accepting of big screw ups with plumbing and electricity than we are with most software.
I'm skeptical of this. There is an extremely large barrier to entry in terms of the cost of the supplies and hardware. And how would you even begin to realistically get practice/experience working on and solving the countless issues plumbers are responsible for, all in different contexts with different setups? And then there's also a safety issue - plenty of environments and tasks plumbers are responsible for can be quite dangerous. Danger and self-learning isn't entirely a non-starter, but it's certainly an part of the 'balance' here.
By contrast software just isn't comparable at all. You can sit at your desk, pay $0, and the only limitations to your experience is the amount of time you're willing to dedicate.
By contrast software just isn't comparable at all. You can sit at your desk, pay $0, and the only limitations to your experience is the amount of time you're willing to dedicate.