To get them built. Electric cars are only viable if people can use them on the same infastructure, in roughly the same way as gasoline cars. A core part of that is a expansive and reliable charging network that spans the nation.

It doesnt need to be "gas stations" anymore, but they need to be as convenient, at least in their own way.

It's common, and arguably one of the most useful parts of goverment, that highly positive but fiscally negative projects will be "seeded" for a number of years with goverment money. This happened with electrication, telecom, internet access, etc. Goverment subsidies the intial infrastructure for profit to occur, and then profit motives take over and the government can end its investment. In this way, the goverment can shift the nation in positive directions, improving its citizens lives. This fucks up at times (see hundreds of billions in broadband investments and the glacial or non existent improvements), but is largely a sound idea.

Thats why Bidens IRA pushed so much money into various green tech, including charging infastructure. If the chargers are there, it solves a core EV adoption problem, which spurs green car tech forward.

To catch up with other countries, as far as I can tell.

The US is way behind in a lot of infrastructure development like mass transit and power grids, so falling behind in EVs is pretty undesirable at this point.

Just because a charger is subsidized, doesn't mean it's subsidized 100% (but to be honest, I'm not sure the actual amount)

The charger you see costs a lot of money. It may be supplied by another large, expensive transformer (I've seen 150kW transformer boxes outside of fast food restaurants, and you'd need several if you have multiple chargers - oh, and they could be much bigger than 150kW). Once you have it installed, they need maintenance and repairs. Oh, and the energy companies are going to charge a lot more for a line capable of handling the equivalent of multiple houses going full blast on 200A service at once... Both installation and supplying so much power, especially at peak times.

That said, I have seen level 2 charging at very reasonable rates, some of which seems to have some kind of government or energy company involvement. Basically a few cents per kWh more than I pay at home.