Yes, you need a place to move between rows. But really the spacing is for proper vegetable growth. Traditionally it's to provide adequate root growth for each plant and not compete for plant food. Planting too closely will reduce output from each plant. So more becomes less, when you want less is more. If you want plants that take up a lot of space try growing yellow and zucchini squashes. Also, you can grow spring/summer/winters gardens if you plan your plot carefully. I've done that with good success. That way you get maximum productivity from your garden. Good luck. Keep us updated.

You are correct about the row spacing. It's used for walking and mechanical cultivation. And as lexusnexus said, it also depends on soil fertility. The more fertile the soil the closer you can plant, to an extent. In a home situation most things can be planted much closer together.

Beets you can plant rows 4-8 inches apart (depends on the size root you want), radishes a couple inches, beans (bush variety) can go a foot apart (although some will say they can be planted closer), and peppers can be 12-18 inches (I prefer them to be at the wider spacing). Tomato and eggplant someone else will have to help with. I've never grown eggplant and I've got very limited experience with tomatoes.

Now when doing rows of different veggies with different growth habits next to each other the above spacings don't really apply. They only apply to plants of the same variety or plants with a similar leaf spread.

Tomatoes will be the tallest so I'd plant them in the back, eggplants will probably be the next tallest, then peppers, then beans and beets, and radishes are quite short. However, you have to remember that during summer the sun is almost completely overhead as opposed to the late fall/winter/early spring when it's on an angle. So even your tallest plants, if your rows are oriented east to west, won't cast much shade on the other plants during summer.

Rodney

If you are working with a new garden I would use the spacing you listed.
If bean get too crowded the blossoms won't get pollinated.

Radishes can go in around the tomatoes at planting time. They will be harvested before the tomatoes crowd the area. Beets can probably do the same. This will free up some space.