cars would be number one. generally the bigger the city, the better the transit. Its usually denser allowing for things you need to get to being closer like stores or schools or libraries. that is the carrot side and on the stick side you have more expensive parking or flat out a lack of parking and usually at least one fee on cars and things are more expensive including gas. so easier to get by without a car and having a car is a larger burden.

Number two is opportunity. Goes back to the density. A large enough city has most anything. You can do most anything when you live there. In the most rural areas you do not have many things you might want to go to and if you do have them you have less options to choose from. In the most extreme like crazy remote places you might have almost nothing and have to take these long stock up trips and grow or hunt for supplementing food and such.

There are likely others but nothing pops out like those two for me.