For example, from this Google search
the middle camera is way more blue in color than the others.
What is the reason behind this? Do these cameras have some special type of glass that results in blue color or is it something else?
The difference is likely due to different lighting setups. The two cameras on the sides seems to be photographed in one setup, and the middle camera in a different setup.
The camera houses will reflect the light from the lamps that are set up to light up the camera, while the glass in the lens will reflect light that comes from the surrounding room. The color tint in the lens is the difference in light temperature between the product shoot setup and the surronding room.
The setup for the cameras on the sides would have a colder light for the setup, for example flashes, and a warmer light in the surrounding room, for example regular lightbulbs. The setup for the camera in the middle would have a warmer light for the setup, pretty much any kind of lamp, and a colder light in the surrounding room, like flourescent light.
As the white balance for the photos are adjusted to the light of the product shoot setup, the difference in lighting only shows up in the reflection in the lens.
I adjusted the white balance to roughly make the reflected light in the lenses neutral, so that you can see the difference between the surrounding light and the setup light:
I think it's to do with white balance. If you look at the housings, the middle camera seems to me to have a much bluer tinge than the other two.
It looks like the whole middle image has a blue tint, maybe due to blue lighting, vs yellow lighting in the other two. Also, note that the lens in the middle one is the newer version of the 18-55 kit lens, while the other two have the older kit on them, so possibly there are different coating with different color.