Business as usual during #TrumpShutdown? That's not how this works. No part of this is essential.
This is going to keep happening, people will keep getting called in to work unpaid until they protest and refuse. I know, easier said than done since there's the risk of no job to return to when it does finally open.
He's basically forcing government employees to work with no pay for things that benefit him and his buddies and/or keep the public the quiet (like sending out tax refund checks) to avoid major backlash over this shutdown. Meanwhile he's turning down every proposal Democrats and Republicans put in front of him. Slave labor? Seems like it.