I've worked fast food. By law, the shake machine has to be sanitized every 24 hours. It takes a solid hour to empty, clean, and sanitize the shake machine (not counting interruptions from customers). It's done in the evening because that is the least popular time for selling shakes. The store is choosing to inconvenience as few people as possible by shutting the machine down when business is slower.

The employees can't refill it and get it going because then the machine would be turned off when it's time to go home, thus requiring them to drain all the shake mix out.

You owe the "lazy" employees an apology.

Grow the hell up already and find another place that's open later and can give you a shake. Freakin' whiner.