Even if that were a necessary condition, it wouldn't be sufficient. You also have to have an economy where investment in machinery makes sense. (I.e. your investment won't be confiscated by corrupt officials or destroyed by invaders.)
Also, humans only compete with machines in a few types of work. For example, you could not use human power to drive most of the things we drive with engines: cars, trains, ships, planes, etc.
> For example, you could not use human power to drive most of the things we drive with engines: cars, trains, ships, planes, etc.
True, but not relevant to the initial, successful commercialisation of the technology. The mobile power plants are a whole step beyond the "lets mechanize labour".
That would be Hernando de Soto's ideas about developing capitalism in the western world as higher order property rights: i.e. a system where you are guaranteed the right both to use what you own and to perform other operations with it: selling to a complete stranger, renting, using it as collateral etc. I still haven't read any explanation as to why it happened in the western Europe but not elsewhere.
Also, humans only compete with machines in a few types of work. For example, you could not use human power to drive most of the things we drive with engines: cars, trains, ships, planes, etc.