

J.D. Power runs surveys which you’ll get if you use PlugShare (and if you aren’t using it, you should to find out about out-of-service chargers!). They publish their results, and a recent publication addresses no-charge and waiting visits:
Non-charge visits and availability vary by location: To better understand the EV charging experience, J.D. Power monitors non-charge visits and availability at public stations nationwide. The findings reveal that the Pacific region has the highest rate of non-charge visits (21%), with 12% of customers also reporting wait times for an available charger. In contrast, the East South Central region has the lowest incidence of both issues, just 7% for non-charge visits and 5% for wait times. Among major cities, EV owners in Seattle (25%) and Los Angeles (24%) report high rates of unsuccessful charging attempts, while a greater share of drivers in San Francisco (18%) and Denver (14%) experience wait times to access chargers. By far, the most common reason for non-charge visits is the charger being out of service or not working properly, which affects 60% of failed charging visits.
It does look like PlugShare has coverage in Europe, but I don’t know if it’s as necessary — from what I hear y’all have much better charging infrastructure. J.D. Power does have some non-US surveys, though I only see Canada and China.