> One thing I've always wanted to see is a mandatory A/B test built into any new legislation
This is what I find great about US and EU (I am from Czech Republic), that in a federal system, you can test the legislation in one state first, and then see the results and this lets the other states to perhaps adopt or avoid that approach.
Unfortunately, strong moneyed interests break that model by lobbying strongly in Washington and Brussels from the start, which I think is a bad trend, but I have no idea how to prevent it. The effect of having more cultural diversity is very hard to quantify economically. (There is also other side of the coin though, which is too much state competition can lead to polarization and war.)
Although sometimes there are things where you have to be careful about this approach - for example, if one state engages in lower taxes or pro-export policies, it may gain, but the same policy enacted by everybody will make everyone lose.
There are a lot of things which work better as federal programs vs state / local programs. Homeless populations spring to mind, if some city's treat there homeless population poorly they can 'export' the problem to another city / state. Where a state with overly generous benefits may see migration.
Education is another with states that export there most educated population having little incentive to subsidize their higher education system. Which likely has lead to the dismantling of state funded schools as people became more mobile.
> Which likely has lead to the dismantling of state funded schools
I disagree this is a necessary outcome. It may as well happen that backward states will take notice and improve their higher education system in various ways.
But I think what you are saying is a fair point and I actually mentioned it. What I would add to my comment is the common solution to this is called "principle of subsidiarity" and it's used EU and Switzerland (which is another example of a federation that often tests different law variations in smaller scale first).
This is what I find great about US and EU (I am from Czech Republic), that in a federal system, you can test the legislation in one state first, and then see the results and this lets the other states to perhaps adopt or avoid that approach.
Unfortunately, strong moneyed interests break that model by lobbying strongly in Washington and Brussels from the start, which I think is a bad trend, but I have no idea how to prevent it. The effect of having more cultural diversity is very hard to quantify economically. (There is also other side of the coin though, which is too much state competition can lead to polarization and war.)
Although sometimes there are things where you have to be careful about this approach - for example, if one state engages in lower taxes or pro-export policies, it may gain, but the same policy enacted by everybody will make everyone lose.