If the stuff is there, meal prep is always faster than Door Dash. Always.
But prep begins with planning, ie.. before shopping.
We have chickens and an endless supply (it seems) of eggs, so there is always eggs when I want something quick.
And, it’s almost embarrassing to admit, since we got the air-fryer, nothing seems like actual ‘cooking’. Ours is a toaster-oven type. It’s always like making toast or playing with the Easy Bake Oven I had in the early 1970’s.
You're absolutely right that it has to start with smart food buying. No pun intended, really, but it's kind of a chicken and egg thing. People need to have the right ingredients on hand for convenient meals, but they also need to shop for new things to even try out and learn which recipes are easy if they don't already know them.
Getting to a point where certain meals are super easy and automatic and you know how to shop for them to have the right things on hand can take time.
When I first switched to vegetarian cooking, I had to go through a whole transition of my planning and shopping and it took a lot of very intentional effort and extra shopping trips at first. Now that it's all second nature to me, I have countless easy dishes I can whip up with what I know to keep on hand in terms of supplies.
If someone is starting from having zero easy options off the top of their head, it isn't at all intuitive how to plan for groceries to make their lives easier.
I've converted many people over to how I cook. They find out how little I spend on food, how delicious my meals are, and how I lost and kept off a ton of weight eating this way, and they usually want in.
It's always a process for me of teaching them to transition slowly, to master a few really easy recipes first and slowly incorporate them into their existing routine. When people make poor choices because of convenience, it's pretty doomed to fail if the solution feels really challenging at the beginning.
I always make them get an Instant Pot and I always start them on this recipe because it only takes about max 10 minutes of work, makes 8 servings, is insanely tasty and filling, and only costs a few dollars for the entire batch:
https://www.apinchofhealthy.com/instant-pot-black-bean-soup/