I think that all the arrondissements have garbage collection but that half of them use civil servants and the other half use private contractors. I'm not sure why this would be the case, but my guess is that the districts that use contractors tend to be on the more expensive side -- you don't really see rubbish in the tourist or commercial districts. Rubbish has resumed being collected in some of the districts, like the one I took photos in, but it's uneven -- some streets are still packed with trash