With how some of this urban design happens it almost feels to be the case at times.
A bit more real of an answer is: federalism. You're assuming the state DoT is entirely in charge of these projects. Lots of different government organizations are in charge of these things, and they don't always communicate well. Cities, counties, toll operators, and others can decide when these ramps are opened or closed. It's not just the state DoT that does these things. There's no single org that can authoritatively say "these are all the roads which are open, right now."
Now, I do agree with you, making such a data set complete and public should be some level of priority. There should be reporting standards involved in defined, standardized formats. These do not really exist, and making such a thing happen is a political question not a technical one.
Like did a bunch of teenagers sneak out at night and build a highway?
How hard can it be to have a process where mapping companies can register with a state’s DoT and get information when they build stuff?