[gerdesj]

You need to shoot the people who are feeding them - that's the logical solution to the problem you posed 8) Their natural predators are now cars because that is how things are now.

An environment is whatever it is at a point in time. You have described how things are around you and that is the current normal. You may not like it or even understand it but that is how it is.

You have to decide whether deer should live within your domain or not. At the moment it sounds like they are a negative factor for you. When you have run out of deer, will you start on the coyotes? When you have run out of creatures with backbones, will you start on arthropodia or amphibians?

[chrisco255]

Not really. The deer that thrive in suburban areas learn to watch for traffic. Even where deer vs car collisions are common, deer multiply well beyond what car traffic takes out. Really, hunting is the only way to thin the numbers.

Deer eat grass, they can thrive almost anywhere in North America just fine with or without people feeding them.

In suburbs they probably need to capture and slaughter some number of them to keep the numbers reasonable.

[pfdietz]

Deer can eat grass, but it's not their preferred food, and they can't thrive on it. They eat forbs, shoots, browse (twigs, buds, etc.) and mast like acorns (they are set up to deal with the large amounts of tannin in acorns).

https://www.msudeer.msstate.edu/deer-diet.php

"Although low quality forages such as mature grasses provide adequate nutrition to animals such as elk and cattle, the quicker digestive process of whitetails requires more readily digestible forages to fulfill their energy and protein requirements. On severely overpopulated and depleted ranges, white-tailed deer have starved to death with their stomachs full of low quality forages."

[chrisco255]

Point taken. Of course, again there is no shortage of shrubbery in suburban environments. And the last point is just what always happens when a species that evolved as prey is no longer hunted.

[pfdietz]

Also plenty of immature grass. See also Canada Geese, which do prefer that.