$4k barely buys a convection oven, much less all the basic furnishings for front & back.
I periodically consider opening a small chocolate shop, then look at the cost and sober up. For a basic suite of kitchen equipment - oven or two, fridge, freezer, range, prep tables, sinks, shelving, pots & pans - even used you’re going to need at least $20k in kitchen equipment, more like $40 k if you buy it new. A type 1 hood over the gas stove or fryer adds another $10-20k.
The last restaurant I worked in was a something like a $900k build-out, 5 years ago. There had been a wholesale bakery there but it was just a shell before renovation. They added a partial second floor for offices, a covered patio area, courtyard/garden area, new walk-in, custom bar & a few built-in benches, restrooms, large hood system. A lot of the old kitchen equipment from the previous location was saved - freezer, 60qt hobart, ovens & ranges, vacuum machine, speed racks, sheet pans - otherwise it would have been more.
So I think the “ugly restaurant” category isn’t realistic but otherwise agree that it’s at least $100k to get the door open if you have to put in a kitchen.
And now that I’ve actually read the article - the place is only 1250 square feet! They spent $560 per square foot