Is it beneficial for governments to subsidize electric car purchases? Are electric cars primarily beneficial for individuals or for companies such as Tesla?

It is beneficial mostly to high income homeowners who have the means to afford the EV itself as well as the cost and legal right of installing a charger for their EV. This is especially true after Biden placed a 100% tariff on the cheapest EVs in the global market just to saber rattle with another industrial power that challenges American hegemony. I kind of already answered this question in two prior answers:

Tesla and Laptop class homeowners.

Third world traditional societies

Why? Making batteries requires different types of metals extracted via mining, mining that is done in low income countries where governments are easily bribed to overlook the health hazards mining creates. When the demand for more and larger batteries that can drive vehicles surges mining operations have to expand to meet the higher demand for raw unprocessed inputs and thus more mining concessions have to be made. More mining concessions inevitably lead to more land grabs with people who have lived and worked on the land being conceded for generations on end which they are inevitably forced to give up after the mining companies and national governments strong arm them into leaving and the projects poisons the surrounding ecosystem killing their subsistence industry that depended on a healthy ecosystem. That is the current predicament for the locals who live near the World Bank financed QMM mine in Madagascar that has poisoned the nearby lakes and rivers with excessive levels of lead and uranium from the process of extracting monazite that contains rare earths used to produce magnets in EV batteries and wind turbines, and ilmenite, used to make titanium dioxide, from the nearby ore deposits. The contamination of their lakes and rivers along with the construction of a physical barrier across one lake that made it a fresh water lake killed off most species of fish the locals depended on for food and their livelihoods, but their national government doesn’t care about the impact because it owns 20% of the mine. This is not an isolated incident. As I pointed out in past posts there are numerous other cases around the world wearing mining operations have wreaked havoc on the ecosystems and communities where they set up and these land conflicts will only intensify as the demand for battery components surges.

Will using electric cars instead of fossil fuel cars actually do anything?

The EV purchaser remains none the wiser because the land grab occurred so far down the supply chain and thousands of miles away on another continent that it never even crosses their waking thoughts that their “clean energy” vehicle can only exist by dispossessing other people in another part of the world.