You can't read anything into that, as you are watching over your locals. Every market has different locals, and some have better PQ and some have worse PQ (due to having a lot of subchannels etc) Also the way Directv collects the signal from them matters a lot too.
You'd might well have different experiences if you watched those NBC & ABC channels on Directv versus watching them on your local cable TV provider and picking them up OTA with an antenna. My local CBS and Fox outlets (one 1080i and one 720p) used to be VASTLY superior via OTA than what I'd get via Directv. Why? Because for the first few years after the HD transition, neither had any subchannels, so the whole 19.2 Mbps ATSC bandwidth was devoted a single HD channel. Now that they have three subchannels each, they are not nearly as good, and there's no real difference from what I get via Directv.
After stations begin to transition to ATSC 3.0 that'll shake things up again, and you might get better quality picking some up via OTA while others will look better on Directv. Just depends on how that transition happens in one's local market, and how Directv is acquiring the local broadcast signals. Only thing you can say for sure if that even if ATSC 3.0 results in locals broadcasting in 4K (personally I'm skeptical) you will NEVER get 4K locals via Directv satellite.