The reason that households generally don't have individual methods of generating energy is that it was generally more cost effective to do that on a large scale for hundreds or thousands of households at once. The details vary from country to country, but what usually happened is that, as different companies got bigger and bigger, with more power stations and grids serving their customers, they got together with other power companies operating in the same area and/or country, and came to an agreement about them all using the same wiring to supply that power. Governments got involved to standardise thhings and/or draw up and enforce safety regulations, and this, combined with cooperation between different governments, has led to things like national electricity grids and the transnational grid that most of Europe connects to. Even larger 'supergrids' are proposed, such as one linking Europe, the Middle East and north Africa, partly because it allows the various sources of renewable energy in those areas to be linked in one massive grid spanning 13 timezones, thus promoting the use of renewables.
However, thanks to climate change, there is a push in many countries to get people to install things like solar panels on their own houses through tax incentives or government grants, so it would seem this is not just permitted, but actually encouraged.