No, they do, but in most cases the effects emerge in the long run. Most laws take several months or years to go into effect, and then more time for patterns to emerge, and even more time for them being actually measured.

Take taxes. In the UK, the budget is approved in Spring (let's say 2020). Any change in income tax or corporation tax will go into force a year later, so April 2021. Individuals must file their returns the following January 2022, with nominal penalties for delaying an extra month. Statistical aggregation then takes place, which can take several more months. So basically, you won't know the immediate effect of a tax policy until almost 3 years later - and that's just for short-term effects! Actual long-term patterns might not be visible before 5 or 10 years have passed. In the meantime, we'll already be debating further changes, while we've not even fully absorbed the previous ones.

And taxes are as straightforward a field as you can have! Legislation on things like building standards typically carries some slack to give people time to adapt, and measuring effects of changes can be very hard even over a decade.