UV light does not just create repairable dimers in DNA bases, it can and does rip DNA apart. Enough exposure would cause more than enough irreparable damage to kill the cell and 99% of the cell being destroyed is certainly not salvageable.
Regional service for the airline is served by Delta Connection. Delta typically charges a fee for all checked bags on domestic flights, with most international flights having an allowance of one or two free checked bags per passenger, depending on destination.
The new fee applies only to tickets purchased after December 6 for flights on or after April 10, 2018. Before the change, basic economy passengers were afforded one free checked bag on these flights, the same as Delta's main cabin passengers. Basic economy passengers traveling before April 10 will still get the free checked bag.