The new test is so stringent that people are failing left and right.
If you've recently had work done to an emissons control function (cat converter, EGR, etc), or removed your battery to perform something on the vehicle unrelated to emissions (installing a new stereo, wiring in an accessory, etc), when you bring your vehicle in, your monitors will likely "not be ready".
The problem with this is twofold. The new OBD2 test logs drive cycles, meaning that you can't just clear your engine code two minutes before the test and expect to pass. You won't. The second problem is if you do this knowingly, and the test determines your vehicle isn't ready, you're on the hook for the $39.95 for the etest even though an actual test wasn't performed. Furthermore, you'll have to bring the vehicle back when there is sufficient drive cycle data, and you guessed it, you're paying another $17.50 for your re-test!