There is a significant amount of just plain NIMBYism, but I think some of the resistance is deserved because people know the developers just want to get in, sell the units, and get out leaving everyone else to deal with all the effects of way more people using the same infrastructure.

Now, if the developers are willing to pay for the infrastructure improvements to handle all the people, that's great, but I haven't seen that happen often, although it admittedly does happen.