What meal for 2 people did you have from Blue Apron that came out to be nearly 4,000 calories? From what I can tell they average around 600-700 per meal, per person.
This one here is 730 calories/serving: https://www.blueapron.com/recipes/spicy-korean-rice-cakes-wi...
This one is 800 and includes a half pound of cheese: https://www.blueapron.com/recipes/mozzarella-ricotta-calzone...
Here's another 750 calorie/serving item: https://www.blueapron.com/recipes/sweet-potato-quesadillas-w...
These are not healthy meals at that calorie count/serving. 750 calories should be right about half of the daily caloric intake for many people. And you're eating that all at dinner? Do you feel comfortable eating an entire box of mac'n cheese for dinner? Because that has less calories than do these meal options.
If you are very small you may need less than that. In that case, eat less.
If they were to ship out 400 calorie dinners, people would be very, very unsatisfied. If you're a small person, you probably don't experience this, but big people that are very active need to eat a lot. I know people that eat close to 4000 calories per day and could easily make room for more.
Personally, as someone on a weight loss journey (unapologetic euphemism for 'fatass'), I have paid very close attention to caloric intake. At my high, I would need about 2200 calories per day to lose weight at the supposed healthy rate of 2lbs per day. If I ate much less than that I wouldn't have energy and would be hungry constantly; this isn't healthy and one of the reasons starving oneself isn't a great weight loss strategy. Of course as I lost weight, my caloric needs changed - 20lbs down I started to need to eat closer to 2000 calories per day.
There are metabolism calculators online; in my case, I was surprised to see they accurately predicted how I would react to various levels of caloric intake.
I would recommend plugging in values you'd estimate for people you know and people you see on e.g. TV. You might be surprised at how different their experiences are in terms of what constitutes a healthy maintenance diet.
For a dinner, aiming for 750 calories per person doesn't seem crazy to me.