What this actually means is that someone is making on-time payments for 20 years (10 if they work for the public sector) and still hasn't paid back the balance. More often than not this means they're paying less than interest.
When I was initially on an IBR plan I was paying roughly 3/4 of the interest that was accruing every month. Do you have any idea how soul-crushing it is to make less than $30k a year, make payments in the multiple hundreds of dollars every months, and see the balance increase?
After 20 years of that, I think you deserve the forgiveness. But not only that, you're then taxed on the forgiveness (which I think is necessary!). So you struggle for 20 years, still have the debt, then get nailed with what could very well be a 5-figure tax bill.
Under most circumstances they have probably paid more to the federal government than you have.
Screw all those freeloaders!