That's because your search engine results are a joke, not because of the DMA.
If I search for 'hotel <city>', I get an ad from Booking.com, then some hotel ad, then an ad from Trivago, then some Google map with hotels (make sense, but all results there are sponsored by intermediaries), then Booking.com, then Booking.com again, then Expedia, then Tripadvisor, then Trivago.
If you only present me sponsored results from intermediaries, then don't be surprised that people only click on sponsored results of intermediaries.