I initially read the headline as referring to maintenance costs, but it's actually because people who rent EVs were using them under the rent to gig economy business they had. As in, people would rent cars to go do Uber Eats deliveries and such, as the EVs weren't being rented as often as expected from regular rental business. The people who rented these EVs were more likely to damage the vehicle than people who rented gas cars, and the repairs for that damage were more costly to fix.

There wasn't a great explanation as to why the EV rentals were more likely to get into accidents, but it's possible that the EVs were more confusing to operate, or more likely to be driven more aggressively due to the acceleration and performance. It's also possible that the EV models they had were more prone to other issues, like blind spots, worse breaking, or insufficient self-driving, but they didn't seem to distinguish between different makes and models as being more prone to damage.