Getting back to the original question...
There are three types of window films/tints that one might use on garage windows. Dyed non-reflective, Solar Reflective, and Frosted/obscure.
Dyed N-R are typical of cheaper auto films, they can cut up to 95% of incoming daylight but only keep out up to 40% of solar heat gain, since they are non-reflective in nature. Reflective building tints, typically silvers and bronzes, can reduce incoming daylight by up to 85% but with up to 80% solar heat rejection. Frosted films let in most of the light but keep out relatively little heat (again, non-reflective). So-called high-performance auto tint films combine dyed colour layers sandwiching a metal reflective layer. Again very low light transmission, but heat reflections in the 50-60% range.
Dyed N-R and Reflectives all will give you good daytime privacy (people can't see in and you can see out, but ONLY during daytime) but no privacy at night. If the lights are on in the garage people can see in, and you can't see them looking!
Frosted films give you the bathroom window effect, lots of daylighting and total privacy day and night. Only thing is, you can't see out either. Ways around this are with a separate peephole viewer, one window not frosted, or a hinged flap/cover over a viewing space.
I use frosted film on my workshop windows. This diffuses the sunlight, sends it all over the workspace, and makes for great work lighting with no glare or harsh shadows.
Some folks worry that a window tint will entice crooks to break in and see what might be worth stealing. Maybe, but if we leave the windows clear, then all the goodies are in plain sight and even more appealing.
