I'm probably not the person to answer this, since cooking's how I relax in the evening, my family bequeathed me with both an old Italian food culture and an old New Orleans food culture, and I rarely eat out because there are only a few restaurants in Seattle that produce food significantly better than what I can toss together in ten minutes when I'm tired and not paying attention.
It is mostly knowledge. For me, convenience is having the meal halfway done. I roast two chickens a month, which provides me with meat for sandwiches and salads, and stock for my soups. I keep bulk frozen goods on hand (fruit, fish filets), and I make my tomato sauce in bulk and freeze it. In the winter I do the same with my ragu. For sauces like that, freeze them in ice cube trays. Do the same with pesto and pureed, roasted garlic. Ten pounds of onions and ten pounds of sweet potatos in the pantry. Black beluga lentils, which are certainly an indulgence, but worth it. Cook up quinoa, millet, and other grains with no flavorings and store them in the fridge. Make a giant pot of soup or stew and eat at it for a week, and freeze the rest in meal sized portions. Buy good bacon bulk and freeze it in packets of about a week's worth at a time. Keep eggs on hand. I live in an apartment, so I don't have any garden but my little herbs in the entranceway, and no chickens, so it's always a nuisance trying to poach eggs, but I'll often keep a bunch of hard boiled around.
I made my own bread once a week for years (except while I was living in Europe, where I bought my bread from the neighborhood bakery), though I don't now since my girlfriend's been trying to cut down on her carbs.
I recently taught yet another of my friends to cook, and started thinking I needed to write a book or a blog or something, since there's all this basic technique that seems not to get passed on. So many folks are convinced that tomato sauce or roast chicken is somehow hard. For example:
Tomato sauce: 4 cups of pureed tomatos, fresh or canned, 2 tablespoons of butter, and an onion, cut in half and peeled, thrown into a pot. Cook on low, uncovered, for an hour or two, stirring occasionally, until it's thickened into a nice sauce. Pour it into an icecube tray to freeze it if you want to use it later. It scales exactly, except that you cook it longer.
Roast chicken: Wash and drain the chicken, rub it inside and out with salt, pepper, and olive oil. Take two lemons, crush their insides by rolling them on the counter while pressing down on them with your palm, then puncture them all over. Shove them into the chicken's cavity. Put the chicken breast down in a pan, and put in the oven on 350F. After half an hour, turn it over. Put a meat thermometer in. When it's about 20 or 30 degrees below done for 180F, turn the over up to 450F to brown it as it finishes. When it hits 180F, pull it out and let it sit for ten minutes or so before carving. The lemons baste it from the inside. Carve all the meat off, then put the carcass, all the organs that should have come with it, an onion or two, and some celery and carrots, in a big pot, fill it with water, and cook it at a solid boil for hours and hours until all the flavor's leeched into the water and made it into stock. Freeze the stock. Ice cubes work if you've got enough trays. I use yogurt containers these days because I don't.
Given tomato sauce or pesto in the freezer, dinner is limited by what you want to put them on. Homemade pasta's also really easy if you get yourself an old style pasta machine. It freezes just fine, too. With stock, soup is very fast. Throw a few nice vegetables in, maybe a little barley, and season it to flavor, and you've got dinner.
The true test of a cook is simple things. How well can you make potato soup and a grilled cheese sandwich? If you can do those superbly, then the notion of ordering a pizza or going out to pick up a prepared meal from the store becomes laughable.
On the other hand, we go out to eat once a month, choose the place carefully, and really enjoy it. Generally it's something that I don't know how to make, or would be far too much work: a Salvadorean bakery that does heavenly fried plantains and papusas; a Japanese restaurant which gets seafood that I can't; a Chinese restaurant that does seafood dishes that I'm just not equipped for; Afghan and Ethiopian, where I don't understand the spice palettes; and several months have been going to an old Mexican taco cart where they giggle at my lisping, European Spanish. Notice the total absence of Italian on that list.
Which is all a long winded way of saying, "Good god, people, just learn how to cook."