Well that would apply to a lot of thing governments spend money on. I think the idea is that governments are better at allocating capital in certain cases (obviously one might disagree with that) than the people/companies who generate the most tax revenue. I mean on an individual level even if solar batteries are profitable people who have sufficient disposable income might chose to invest it into the US stock market (if it still offers better returns) amongst other things than into something that benefits the Australian economy or society.

> that's what loans are for

Upthread: "interest free loan of 15k" https://news.ycombinator.com/item?id=48904009

> Except that there is no additional money, its just your own money but now there are strings.

I understand what you mean, and yeah, "it's just your money", but also, it really isn't. Poor people have to pay taxes, no way around it, getting them back as subsidies is still better for them than not getting it back at all. The choice isn't "Keep the money or have subsidies", the choice is "The money goes to other stuff or get subsidies".

> On top of that, that still isn't necessary for things that save a non-trivial amount of money, because that's what loans are for. If it has a $100/mo loan payment and saves $150/mo on the electric bill then you take out a loan or buy it on an installment plan and don't need to have any accumulated capital in order to do it.

Are those interest-free or managed by for-profit entities? Because "loans" are vastly different things compared to subsidies, but I'm guessing you already knew this.

> Why would anybody want that either, instead of just not taking it from you to begin with?

Because "not taking it from you to begin with" isn't a practical and realistic alternative, that's not how the world, and especially taxes and government works...