I've been trying to figure that out myself, and I think it involves things being locked away at the start, and unlocking them as you meet certain criteria.

Currently, the only criteria is money. You can literally just buy anything at any time, if you have the cash. Tractors, land, buildings... Anything. Almost all of it is instant. The few things that aren't instant are just annoying and not worth the effort.

There is a mod that unlocks tractors according to the year, matching them up with when they were released. That's at least a kind of progression, but still not what I'd enjoy.

In short, I think I want it more gamified and less of a straight simulation. Unlocking better tractors would mean reaching certain goals while using lesser tractors, etc. Motor Town has this. You need to do a certain amount of work with lesser machines to unlock the later ones. You also need the money.

But it would also go beyond what the game has. For some reason, you can be hired as a contractor for things, and rent the necessary equipment for fairly cheap. But as a landowner, you have to micromanage that situation. It's up to you to have the equipment and actually be ready to do the work before you can hand it off to an AI worker. And they're often terrible at it, especially with the lesser-used machines, like (according to a bug report I saw) carrot harvesters.

The game absolutely nails simulating driving a tractor. But as a "game", it fails.