You're not wrong in being surprised by how expensive the US is vs. the others. I'd be really interested in seeing more cities on it now to see if the trend continues to hold up.

I think the best explanation is probably that people in the US are less likely to do the cleaning themselves, but that's a pure guess. The reasons for suspecting that are: my impression is that the cheapest ones seem to correlate with where I imagine people being less likely to hire someone else to do something they can do themselves; perhaps connected to this, I'd suspect cleaning services in the US are much cheaper than other places in your data because of different minimum wage laws.

I also wonder about the size of the homes being compared. I think that the size of the homes in the US tend to be large, while Paris and Berlin are known for having small apartments.