[future1979]

If you make the breach cost infinitely high, how is that not a modern form of slavery?

[pjc50]

It's not infinitely high? In practice the worst it's likely to be is "actual damages" - costs directly incurred by you quitting. http://employeradvice.org.uk/what-to-do-when-staff-quit-with...

Modern slavery is things like confiscating the passports of your immigrant workers so they can't escape.

[Karunamon]

Because the contract is voluntarily entered and the penalties for breaching it are purely financial.