And, while you should absolutely be able to modify your house, the reality is a lot of other buildings are off-limits to you or purpose-built for a specific recipient or cause. Indeed, a huge amount of software is designed to be sold to specific contractors and not to the public at large. Nor will the public realistically have the chance to modify most of the software they interact with, either because they're just circuits, dumb terminals or another reason.
Thirdly, software is permanent, modulo bit rot. That is to say most people can be satisfied entirely by existing written solutions. Simple task automation, scripts and macros can be self-taught if the person sees an opportunity. Actually creating legitimately new things requires a deep proficiency in a problem domain that a pedestrian knowledge of programming will not satisfy.
Also, if you're going to promote ideals for governments, I strongly suggest you promote free software, not open source.