Where I live, two fixed wireless ISPs have about 75% of the market. One offers only NAT, while the other offers only NAT on all but their most expensive plans.

Where I live, two fixed wireless ISPs have about 75% of the market. One offers only NAT, while the other offers only NAT on all but their most expensive plans. So in my area, 75% of the internet traffic comes from just two IP addresses. Moreover, because there's only one backhaul provider, those two ISPs, the county offices, the hospital, the public library and the schools all have traffic originating from a smallish set of addresses in the same AS. Probably the same class C, but I can't say that for sure. Reviews coming from the same IP is a useful signal for detecting fraud, but it certainly shouldn't be considered proof positive.