In a row isn't really the argument that reflects reality. The question is: how often to you drive more than 300 miles without being able to stop for a few hours at an out-of-the-way re-charging station that is compatible with your car. The answer to that (when you look at the slow re-charge rates) for me is: quite often. And that "few hours" could actually be a few days.
I don't know where you get the 300 mile range number, Tesla's own literature states up to 265 miles" EPA Certified", which if anything like EPA MPG then the way most American's drive means more like 200 miles of actual range. When you don't have access to your high current charger at home it takes an hour to get 3 miles of charge from a standard wall outlet. Every time I have a discussion with someone about these cars they produce these great sounding numbers, then you read the actual information and things have a much more grim look to them.
As for your specific question about why I drive 21 miles to the butcher: because I prefer buying locally sourced food whenever possible. The only butcher I know of in the Phoenix area that sells local meats is about 21 miles out of my way between work and home. I also travel out of my way to purchase locally roasted coffee and locally produced milk, eggs, veg. Generally the lower prices of the items I purchase offset the minor amount of diesel I run through my engine getting to those places in a consolidated trip. 21 miles for me is less than 1/2 gallon.
When I go visit my friends in northern AZ, that's a 140 mile one-way trip in mountains and I don't think the Tesla would make it that far on a cargo and there are no exits or services for the majority of the trip.
There are MANY use cases where pure electric just falls flat. So many that I think most people would encounter them fairly regularly or at least fret they would. That means that for most, or at least many, people an electric has to be an additional vehicle they use for specific tasks.
But that aside: why are you condemning someone's life choices just because they don't align with the marketing pitch of an all-electric car?