Nearby networks won't harm your signal to noise ratio unless there is active traffic. Most of the time, 90% of the 30 SSIDs you see nearby are mostly inactive.
Anyway, Ubiquity and commercial gear in general just has better software and hardware design.
* The UAP‑AC‑HD has been around for at least 5 years and still gets updates. Wifi is full of weird bugs so its impossible to release a new chip set bug-free. Consumer gear just doesn't get the same duration of support as commercial.
* These access points are designed specifically for setting up networks with multiple APs and lots of nearby networks.
* These APs are just access points and offload routing and even their UI to a router and management server. A lot of consumer gear uses/wastes a lot of RAM on their fancy management interfaces.
* Exterior profile stays the same. Consumer gear companies spend a lot of time & money on marketing and redesigning the 'look' of their products which diverts focus.
* Better management/software: All the Unifi APs use the same management server software which consolidates features and fixes. The software also has a lot of performance related features like disabling/limiting the slowest speed enabled on the 2.4Ghz and 5Ghz network.
Really the last point is a really big one; consumer gear (besides new consumer mesh networks) is often sold on having great range/coverage but these can cause the whole network to be bogged down by a single device operating in 802.11g or older mode. Commercial gear expects you to use multiple APs to satisfy coverage but has the features to prevent network degradation.
Anyway, Ubiquity and commercial gear in general just has better software and hardware design.
* The UAP‑AC‑HD has been around for at least 5 years and still gets updates. Wifi is full of weird bugs so its impossible to release a new chip set bug-free. Consumer gear just doesn't get the same duration of support as commercial. * These access points are designed specifically for setting up networks with multiple APs and lots of nearby networks. * These APs are just access points and offload routing and even their UI to a router and management server. A lot of consumer gear uses/wastes a lot of RAM on their fancy management interfaces. * Exterior profile stays the same. Consumer gear companies spend a lot of time & money on marketing and redesigning the 'look' of their products which diverts focus. * Better management/software: All the Unifi APs use the same management server software which consolidates features and fixes. The software also has a lot of performance related features like disabling/limiting the slowest speed enabled on the 2.4Ghz and 5Ghz network.
Really the last point is a really big one; consumer gear (besides new consumer mesh networks) is often sold on having great range/coverage but these can cause the whole network to be bogged down by a single device operating in 802.11g or older mode. Commercial gear expects you to use multiple APs to satisfy coverage but has the features to prevent network degradation.