As the saying goes: 9 you're fine, 10 you're mine
I don't mind speed so much as careless driving. If someone is going the precise speed limit but is all over the road or tailgating or distracted that's way worse imo
A lot of small towns pick speed limits for weird reasons. Sometimes they want to keep dust/noise down, or a particular area is known for fatal crashes. Other times it's just how it always was and nobody thinks twice about it. NotJustBikes has a video on how speed limits are usually chosen