I think a lot of this is about perceived value. A gardner gets to see the products of their labour around them every day. A software developer at a bank might write lines of code and never even know when they are run, but those lines of code might, protect against a risk that would otherwise have brought down the company, or optimise investments for a pension fund that help generate additional tens of millions of dollars for people's pensions over the lifetime of the code. A lot of code makes only a tiny difference, but it can make that difference for millions of people over decades.