Aside from "moral outrage" style concerns ("AI is bad for the environment", power consumption, water consumption, or "datacenters benefit rich people, rich people bad, so datacenters bad"), I've heard of specific bad examples how datacenters (allegedly) negatively impacted the surrounding population:
- Noise (from fans to generators to possible infrasound concerns)
- Air pollution (from data centers semi-permanently running on generators)
- Electricity prices (although I don't understand how this is supposed to work)
- Water consumption affecting the population (water restrictions, price increases, water table dropping)
Many of these are one-sided stories told from the perspective of the residents that I didn't try to verify, but I suspect some of these concerns are legit.
The company building the datacenter has a lot of incentives to cut corners and/or cause some of these impacts, externalizing its costs (e.g. by saving money at the expense of noise emissions, running the DC on unpermitted gas turbines to be able to build a DC where there isn't enough grid, negotiating clever deals that benefit the company but screw over the utility forcing it to raise prices for others, using groundwater for evaporative cooling to make cooling cheaper, etc.)
The company building the datacenter also likely has a lot more experience while the people of the town and the town itself are doing this once, so there is an inbalance in experience that makes it easy for the company to get away with some of these.
There is very little benefit that the people of the area can expect from a data center - as I understand it, there are very few jobs in one past the construction phase, even the construction jobs are often filled with experienced travelling workers, and given the negotiation imbalance, a town seems likely to get screwed on any contributions that the data center promises.
Maybe the solution would be some kind of framework/organization that guarantees (ideally with binding, well tested contracts) that the datacenter won't be a nuisance, builds a reputation for being reliable, and in exchange, companies that work under that framework can expect quick approvals and less pushback.
Until that exists, or companies start offering guarantees up front (e.g. guaranteeing a certain power price or noise level), I'm not surprised that people push back (especially if the company building the data center has screwed up in the past).