Tbh half of them are failed or wannabe mechanics who are lazy blighters.
If you’re trade you need to take them to a test station that knows they will NOT be doing any remedial work. ‘My’ MOT man gets the MOT inspections & nothing else.
Mind you, in response to TWERP, blast it around the block & retest but if the exhaust is knackered just replace the exhaust components. Shop around but Fiesta exhaust bits are for pennies & there’s a limit to how much penny pinching you can do in this game - patching up £30 exhaust components makes you look a twat in my opinion.