I think you're getting confused as to what the railroad considers as "leased". Locomotives are commonly bought on 15 year equipment trusts and the railroad has the option to buy them at the end of the trust. That's why the bad performers are often parked at about 12 years and retired/returned at 15 years.

Didn't EMD make some kind of special deal to "lease" UP 1,000+ SD70s after the whole SD90/43 debacle to keep their business? Long term leases aren't unusual - remember BN's Oakway and LMX units? And all those ragtag GP38ish units that UP had leased for a while?

Nothing new - it's all a money game to keep the government and investors happy. Lease units are treated differently on the books. They can buy them and run them into the ground, then if they spend enough money on rebuilding them they can consider them as "new" and depreciate them all over again. It isn't unusual for them to sell the rebuilt locomotives and lease them back. Sometimes it's to themselves for tax advantages - remember SP's own Equipment Company?