That’s a bit of an ad hoc reasoning. There are plenty of job settings where you’re contracted for a specified period, and there are a lot of highly competitive markets where losing an employee means your direct adverse firm gets him. Top solicitors and programmers e.g. or academics. Basically any in-demand high skilled practice.
As to purchase/sale value that’s a pretty bizarre thing to begin with. It treats football players as property not contracted individuals.
I do wonder if a club ever tried terminating a contract on account of performance. I only find examples of gross misconduct but not of a player becoming a fat tub of lard with a season ticket at McDonald’s like Tanguy,
It's not just football, it's almost all professional team sports. Players are tradeable assets with a value to their team.
As for other jobs where there is a specific employment period, they, as well as sports pros will have clearly defined ways of either party breaking the contract. If that non footballer is a valuable asset to their employer they'll probably have a long notice period and be held to it to the day.
The big difference between sports teams and general employment is that a team can only have a certain number of players. That means there's often players that are no longer required but also still hold value and who you wouldn't want playing against you. As a club, you have to try to recoup your outlay and ideally protect yourself from the sale biting you in the arse.
I hate the football transfer system. It's been sent absolutely mental since the transfer window became a thing. The money is ridiculous and making it harder for teams to compete.
On a related note, I see the media are getting their claws into the women's game now and egging them on to spend £1m on a player.
Why? Why not instead focus on giving fans VFM? Instead of making it yet another obscene greed and money show, focus on levelling the playing field and making all teams more competitive. And do it without passing huge costs onto the fans for merchandise, tickets and subscriptions.
And ffs, don't take money out of the mens game either, as that'll just push those costs through the bloody roof more.