The plexiglass wall is meant to dissuade McDonald's customers from getting too far inside a restricted area. It's called a subtle hint. But not everyone picks up on that. Andrew Miller of Rocket News 24 writes:
Apparently, some McDonald’s customers in China are creating a reputation for themselves by exhibiting “overly familiar behavior” towards the staff. This problem became a hot topic online recently when someone snapped a customer completely ignoring the rules of distance etiquette.
Such behavior is reported to be occurring at the “mini” McDonald’s branches where soft cream, desserts, drinks and the like are served. These branches, while not so common in other areas of the world, are very popular in China. These restaurants are installed with a clear perspex screen, similar to that of a ticket booth office, that separates the customer and staff, with a tiny window for the exchange of money and delicious food and drink.
However, as can clearly be seen in the photo above, knowing no shame, one customer thrust their entire upper body through the small opening. Just quite how he pulled the feat off remains unclear but looking closely, you can see that he’s even managed to get his elbows right inside and seems to be waiting rather excitedly for his order to arrive.