Unlike some other replies, I kind of agree with a sentiment (maybe because I did a fair amount of physical labor), but one very important thing to realize is that salaries are not about "what's worth what" and fairness but about supply and demand. Developers get paid more because their productivity allows that and not a lot of people can do what they do. While almost anyone can be a landscaper. And supply and demand in inflexible markets leads either to runaway high or deep bottom price.
Supply and demand is what gives people incentives to do and produce what is most needed and conserve things that are scarce, for the benefit of everyone. Anytime anyone tried to get rid of them completely it ended in poverty and misery, not a more just system.
Having said that, I sympathize with arguments to nudge things toward more just/equal outcomes recognizing supply&demand can be quite inhumane - after all it's a mechanism, not a goal in itself. Some UBI etc. could be an efficient way to help.
Having said that, western world spends huge amounts of money on public education for everyone, and after all that lots of people can't do anything fancier than tiding up a garden. It's a huge waste of resources. Future manual labor workers could start working after quick and efficient elementary schools, and start building wealth sooner to offset their lower productivity. But boy, no one is going to have conversations like that.
On all sides of all debates there's just bunch of irrational people trying to tweak a system that is too complex for them to understand.
