As U.S. airports struggle with fewer Transportation Security Administration workers during a partial government shutdown, some social media users asked why a fee collected on every airline ticket isn't being used to pay TSA agents.

Atlanta's Hartsfield-Jackson International Airport advised travelers to arrive at the airport four hours before their flights. Social media posts show security lines at ATL wrapping around baggage claim and outside the building. Houston and New Orleans airports warned travelers about significant wait times and closed checkpoints.

TSA agent absence rates have tripled since the Feb.14 start of the shutdown, the Department of Homeland Security told Business Insider. Unpaid workers are frustrated; in some cases TSA employees report taking other jobs to pay their bills.

The government couldn't temporarily shift money to ease the shutdown-related TSA shortages, said Joshua Sewell, director of research and policy for Taxpayers for Common Sense, a group that tracks the federal budget.

Neither the language in federal appropriations bills nor the section of the U.S. Code that authorizes the fee would allow such a transfer, Sewell said.