I feel as if the fundamental issue with speed limits is that they often feel arbitrary and infantilizing. If the roads are designed properly then you don't really need them except perhaps as a warning (e.g. the German autobahn isn't unlimited on sections that have tight corners).
My residential street in London is a 20mph limit. But it doesn't need a limit because it has speed bumps frequently enough that if you care about your suspension at all your max speed is average 15ish anyway.
Then there's the main roads leading into town which are also 20mph limits, but are double lane roads with fairly wide lanes. Some of them even have metal dividers.
It fundamentally makes no sense for the limit to be the same on both of those roads. One of them is a proper thoroughfare with a high design limit that was 30 until very recently (probably 40 or higher "back in the day"). The other is a neighbourhood that only really the residents and visitors have any business driving on.
My residential street in London is a 20mph limit. But it doesn't need a limit because it has speed bumps frequently enough that if you care about your suspension at all your max speed is average 15ish anyway.
Then there's the main roads leading into town which are also 20mph limits, but are double lane roads with fairly wide lanes. Some of them even have metal dividers.
It fundamentally makes no sense for the limit to be the same on both of those roads. One of them is a proper thoroughfare with a high design limit that was 30 until very recently (probably 40 or higher "back in the day"). The other is a neighbourhood that only really the residents and visitors have any business driving on.