Structurally this practice is a lot like the preindustrial precursor of taxation, when governments would sell monopolies on the import or production of things in exchange for a lump sum. When obsolete government practices persist, they tend to be pretty sinister.
"When obsolete government practices persist, they tend to be pretty sinister." How might you propose to compensate people who, in good faith, bought taxi medallions (a legal practice)? (Or do you feel that's not necessary?)
The IRS rules http://www.irs.gov/publications/p535/ch08.html state you have to amortize/depreciate the license over 15 years (180 months). So, any licenses that are 16 or more years old, have already been written off in full, so, a lesser amount would be needed to compensate the owners.