Local Map Pack - What the F#ck?

Seriously, the local 3 pack is incredibly frustrating. Is there even any algorithm reasoning behind their ranking with the map pack, or am I completely missing something. There's a large amount of businesses with 1 to 3 star ratings (and maybe 1 to 3 actual reviews) ranking higher than my clients, and other businesses, with 10+ 5 star reviews and 4.5+ ratings.

What am I missing?

Their citations are disastrous.
Their backlinks are minimal.
Their not even in SERPs.

compare others with you/your testing, NOT others with others.

Local map search is all about proximity to the searcher. It is because they are closer.

Proximity crushes all other ranking factors.

What type of websites are these categorically?