Actually, 800 is quite a sensible number. At an average speed of 60 miles per hour (aka, factoring in driving / bathroom / meal breaks), that's 13 1/2 hours of driving - a good day's drive. Throw in a few more hours driving time / a couple hundred miles more range if you charge while you're taking your breaks. Once you get that sort of range, charge speed becomes virtually irrelevant because it happens while you're sleeping (and getting ready for bed / getting up in the morning). A regular Tesla home charger could handle that sort of load.
I agree with you that a half hour charge isn't actually that onerous, but it definitely will scare off people who are used to filling up faster. And charge stations that can do half hour charges on 300 miles range (150kW+ for an efficient car, more like 250kW for a light truck) are exceedingly rare as it stands. A charger that powerful isn't some aren't some little wall box with a cord hanging off of it, it's the size of a couple soda machines put together (bigger if you add a battery buffer so that you don't need a huge power feed) that feeds so much power that its cable has to be liquid cooled and which costs around $100k installed. Ten minute charges are, of course, around three times that size. I've only ever come across mention of *one* charger in the ballpark of the required 750kW to charge a 300 mile light truck in 10 minutes - an 800kW device custom made a couple years back for the US Army Tank Command. I have no clue what it cost, but I'm guessing "Very Expensive".
I'm not saying that the problem is intractable, by any stretch, I totally believe that we're going to transition over to EVs. I just question the sort of time scales that a lot of people envision. The average car on US roads is 10 years old. Implying an average 20 year lifespan. And many cars don't get scrapped then, they just go to the third world. Even if you suddenly switch all new car manufacturing over to EVs, you're talking decades to replace them. But of course you can't just switch over like that - even if everyone was right now sold on the concept of EVs with current tech, you're talking at least a decade, possibly more, to tool up to that level of production. But of course, not everyone is right now sold on the concept of EVs with current tech.
Realistically, you're looking at maybe a 40 year transition. I hate to say that, because I love EVs, but I'm not going to just pretend that the reality is other than it is.
I'll also add that while fast chargers are big and expensive, the size and cost actually are comparable to building a gas station on a per-pump basis, and the economic argument works out for making them even if there's only a reasonable (50% or less) surcharge on the electricity sold and if they're only selling electricity a couple percent of the time. But you need to get a couple percent of the time usage to economically justify them - one person stopping for 10 minutes every few days just isn't going to cut it. And not every EV is going to stop at every charger even if they're driving on the same route - if your chargers are that far apart, then that means you're pushing people's range so much that they're not going to be comfortable driving that route. All together, this means that if you want to have fast charging infrastructure economically justifiable in an area you need high EV penetration, where several dozen EVs driving long distances will be going by each charger every day - even out in the boonies. And when you're talking at prices on the order of $100k per unit, you're no longer talking about a range where peoples' goodwill toward EVs or interest in having a loss leader outside is going to pay for them.
Basically, while busy interstate routes on the coasts and the like can economically justify them with a small fraction of a percent of people driving EVs, out in the boonies, they're going to be stuck with smaller, cheaper, slower chargers for a good while. Unless people are willing to pay a big surcharge on the electricity sold, that is (500% surcharge instead of 50% = 1/10th as many vehicles needed).