Like all pension funds, the contributions were calculated based on actuarial estimates of how many people were likely to survive, and for how long, as well as estimates of how much investment income was likely to be earned by the fund.
The assumptions that formed the basis of those estimates were just that - assumptions. People are living longer, and investment returns from the sorts of investments permitted to pension funds are less than expected.
So there are projected shortfalls in the pension funds.
In the UK, there is a government fund available to help make good on some of the shortfalls, but in addition there is legislation that:
a) makes non-UK parent companies (Eastman Kodak) liable for the UK pension obligations; and
b) gives the government fund priority over other creditors in a bankruptcy.
So in the case of the UK pensioners, there was a government with a big stick that forced the other creditors of Eastman Kodak to settle for less money.
To a great extent, the actual pension payments for most Kodak employees are reasonably well protected.
Where there is a massive shortfall is in those countries where things like medical services benefits are both absolutely necessary and unconscionably expensive - essentially the USA.