First off, great work and I love your line-work, designs, and attention to detail. Even your color palette is spot on!
I am offering critique based on perspective based on your text above, but know that there are other (minor) improvements you could also do on your values and composition to increase the readability of the image.
First off, I noticed that your background is a bit "stiff" and takes away from the image a little bit. I cropped it out and immediately the image felt more organic to me (see result below).
Second of all, your camera's viewpoint is situated slightly ABOVE the crowd, looking down. The service counter is already done using this perspective. This means that there should be a vanishing point for the vertical lines in the drawing, as seen on my second iteration above. By just transforming the background to account for this third vanishing point, immediately the perspective felt more "right" to me.
Also, as a suggestion, I desaturated the background to give more attention to the bright and vivid characters in the foreground.
Bottom-line, try to keep the background consistent with the foreground perspective and you're golden!