It seems TSA is getting more lax these days. Yesterday DH & I were allowed through a TSA Pre section at Chicago O'Hare without the authorization on our boarding pass because Spirit doesn't participate. However, it was very empty, unlike the security section in front of Spirit. We happen to have TSA Pre status but there was no way at the time for TSA to verify this. We liked the convenience but shouldn't have been allowed in without a Global Entry card or passport.
Only those with "trusted traveller" TSA-Pre vetting are supposed to be allowed through those lines, & it prints on the boarding pass. You don't have to remove shoes, liquids, or computer. TSA-Pre used to be available to those with frequent flyer elite status but now requires an application, fingerprinting, interview, & a fee. Global Entry is the better deal -- for $5 more, you get expedited entry into the USA plus TSA-Pre, & it is good for 5 years.