For instance say you lower standards for building bridges, how do you assess the success? First you may notice nothing, because all bridges under construction stay with their design, so consequence 0. After a few years, construction costs may go down because the new standard allow to cut some corners. Great! Success! Now 30 years in the future maybe suddenly the bridge has a failure that costs 20x the savings at the time of construction. Well suddenly not great. But changing the standard at that point would not fix all the bridges built over those 30 years.

Evaluating public policies is often very hard and it's sometimes only possible a long time after. I would also say that weather or not a policy is good or has positive impact has little impact on winning or losing elections. Lots of terrible policies can win you voters. Just like building the best product is not the easiest way to make money. For both goods and elections, playing on emotions works a lot better.

Sure, maybe if participation dropped suddenly to 20% there would be comments and reactions, but anything over 40% would barely get a few curious articles and no real difference.

I remember when you couldn't go anywhere without smelling cold tobacco, even in trains and buses, not even talking about might clubs and restaurants... Now even outside many smokers are considerate and will avoid smoking in your direction, especially when you have kids, which was definitely not the case 20 years ago!