Not everywhere. My car charges off an average of 80% renewables (mostly hydro and geothermal), right now it's 95%.
But it is definitely something you need to take in to account when purchasing, an EV isn't right for everyone.
Whenever you do the real world calculation for what an electric cars CO2 profile looks like it turns out to be the same as a gasoline car unless your country is majority nuclear.
Not at all true: https://www.carboncounter.com/
US-specific but you can even pick a state and it will use the generation mix of that state
At night the sun doesn't shine.
The mix is mostly coal or if you're lucky mostly gas.
This is the type of bullshit I mean by doing real world calculations.
For you to prefer charging there your employer only has to charge you less during the day than your utility charges during the night, so the day/night rate arbitrage can easily pay for the metering hardware and installation (at the next opportunity to install without having to dig the parking lot up just for the chargers), with the rest being profit to incentivize the managers to install/offer this.
In my state (idaho) at night the power mixture is primarily renewable/clean because of this.
It's inefficient but not hilariously so. Modern ICE are quite amazing technology.
Combined gas turbines (you know, the energy source that powers your electric car) are about 60% efficient for the really good ones, minus 5-7% transmission losses, minus 10-12% charging losses, minus 20% loss in cold climates, lands you at around 35-40% efficiency from fuel source to the wheel.
The Atkinson-cycle engine in the Toyota Prius gets around 40% give or take some losses in the drivetrain. Electric have plenty of upsides, but for some people with cheap gas+high electric costs+cold climate you would honestly be better driving a hybrid.