You are mixing up gardening leave with non-competes. Typically, they have both.
(Eg for a recent job, I had six months of gardening leave, when they paid my base salary, and then another six months of non-compete.)
> [...] but with regards to the article I doubt anyone is forced to choose between working for a trading firm and starving.
Indeed! We don't need welfare for well-off folks. They can fend for themselves, and we can focus limited resources on the poor (and those who want the help).