I have a 2021 SS9 and regularly charge in the UK. In general, the main problem is to find charges that are unocuppied. I very seldom have had to walk away from a charger, but it often takes more than on try to initialize. Some of the older chargers (BP, POLAR, etc) are more prone to issues. Due to availability, I try to use larger groupings of chargers (Gridserve are great!), this way is far more likely there isn´t a queue and if a charger doesn´t cooperate I try the next one.
That said, sequence and even how you hold the cable during initialization can make a difference. I had a DC charge controller installed temporareily in the SS9 (while diagnosing variations on DC charge amps and early "DC Balancing") and while I was always able to charge, I almost always had to try several times. This went away once the controller was replaced (the DC "bouncing amps" was fixed separately by a factory rep.
Heck, I am on my way back from a 2,185 mi. (round trip) in the UK and Spain charged on the road over 34 times and did not get stranded, I did encounter some non fucntioning/malfunctioning chargers, especially in Spain though.
