I am aware, but like I said, the Evero is better for stopping at South Parkway since there would be less selective door opening. Platforms 1 and 2 at South Parkway are 124 and 138 metres respectively. A seven-coach 807 with 26-metre coaches is 182 metres long, so you'd just about squeeze five of those coaches in the platform. Meanwhile a 9-coach 390 is 217.4 metres long and can't offer the same SDO, and even where the eleven-coach units don't fit you can only cut off the rear two coaches.Erm, a seven car Evero doesn't fit in Liverpool South Parkway either. And Pendolinos don't fit everywhere they currently stop anyway...
However, as pointed out we are kind of getting off track from the original subject of compulsory reservations, which seems to have been answered already. Any compulsory reservations would've been a product of the pandemic era and are most likely no longer an actual practice. Plus if reservations were compulsory than the unreserved coaches on both 390s and 807s would be redundant.