I think you missed the analogy. Firstly, it isn't about the amount of work required, because growing good tomatoes requires work as well. Yes, a tomato seed will produce tomatoes on its own, but so will cannabis produce flowers. But in both cases the product might not be as satisfactory as you'd like. You may lose some tomatoes to bugs, and they may not be very big. Same with cannabis, it may be seeded out if there are males around.
Secondly, I think the analogy was more about the enthusiasm a home gardener has, where tomatoes are often something they would grow. So the poster above meant that they'd rather cannabis to be regulated in the same way tomatoes are: you can grow them without regulation at your house, but if you want to sell them commercially (to stores and restaurants) then further licensing is required.
