Spaghetti sauce doesn't always include meat, but, even when it does, meat is only playing a supporting role. The sauce is slightly runny, and it's mostly about tomatoes and herbs.
That can be good. But I have always liked a meaty sauce, which is probably why I prefer a ragù to a typical bolognese sauce.
And I think I have finally settled on a formula for making a marvelous ragù to accompany pasta. I made a ragù a few days ago -- two days later, it was still excellent -- using equal portions of ground pork and ground veal.
A key is not to overcook the ground meat. I have had great results by cooking it most of the way in a skillet and then transferring it to a dutch oven, adding equal parts of red wine and a mixture of chicken and/or veal stock. You want just enough liquid so that the meat will stay moist.
Then I place it in the oven, covered, and cook it at a very low temperature (225 degrees) for about 60 to 90 minutes. This is what braising is all about.
I take it out once to stir it and add some herbs (usually thyme and oregano) about a tablespoon of minced garlic, and a 1/4 cup of onion or shallot (chopped very fine).
Then I finish it on the stovetop (over low heat) and I add a tablespoon or two of flour just to thicken it up and add body.