> my employment contracts have never included guaranteed severance
My assumption was that we would not be talking about "unpaid severance" if there was no severance defined in the first place.
> Are you European? Maybe it's different there.
Generally severance is not legally mandated, but can be mandated under some specific circumstances, e.g. no-notice termination. Usually it is similar to US: either defined in collective (union) agreement or part of termination contract.