Here is a step-by-step view of Conventional Auto Body ( Nail Gun) Repair vs Paintless Repair. That a friend Ricky put together years ago to show the diffences.

Before conventional repair and paintless dent repair

Before conventional repair and paintless repair

After repair
left paint is removed with a grinder so a pull pin can be welded on
middle after the Paintless Dent Repair method with an unprotected repair tip
right after Paintless Dent Repair method with a protected repair tip

The backside of panel after the 3 repair methods
left Welded pull pin paint burned off paint so it can rust.
middle Paintless Dent Repair with an unprotected repair tip slightly scuffed no chance of rust
right Paintless Dent Repair with a protected repair tip left no scuff marks and no chance of rust

This is what the backside of the panel looks like, The shop did not even paint the backside so you can see it is now rusting after several months

This is the outside of the panel repaired with conventional repair methods

These insurance-recommended production body shops ruined these customer’s cars. How much do you want to bet they did not paint or undercoat the back sides of the panel? Wonder how these cars are going to look in 6 months to a few years when all the primer shrinks. A quality shop like mine would have used (PDR) Paintless Dent Repair / Hybrid Repair Method to eliminate or reduce 95% of bondo filler or made the insurance pay to replace the panels.