https://www.eff.org/issues/real-id

Real ID creates yet another nation-wide sized database of all our different types of IDs into one linked whole.

As is the case, whenever a data base is created, it's either misused or abused purposely or it's hacked and compromised.  This new huge database is going to cause more identity theft, and more unauthorized surveillance, that's just a given.  And, it won't stop people with bad intentions, they have access to technology  too, so they can and will just create better fake documents.  It's like an information technology arms race, and you already lost because the technology is and has been already been compromised.  

Due to common machine readable provisions, anyone who can get their hands on very simple machine reader technology can and will have many opportunities to also grab more information about you than you'd ever want most folks to have.

The money concern is the feds don't pay for the huge costs of implementation.  And it is costly.