We can't hang lights on deer. That doesn't mean we shouldn't try to be safe elsewhere.

Also, people talking about driving slow enough to avoid deer are delusional.

A 65mph rural highway may have a 60 ft ROW, making it 23'9" from the trees to the middle of the near lane (30 feet to the center minus 6'3" for a standard 12'6"lane).

A white-tail deer can sprint 35mph, which comes out to just over 50 feet per second. So you have half a second between the trees.

A professional driver on a closed course with new tires and a dry road can control a car braking car at about 32 fpsps (1g). Clearly everyone who says deer can be avoided easily ate perfect drivers, so let's go with that. Let's also assume they have an absolutely perfect reaction time of zero.

Assuming you have impossible reaction times, the skills of a professional, and all other perfect conditions... you can certainly avoid hitting any deer - so long as you're driving under 9 mph at all times.