Here's an ad from Picture Post magazine, which you will recall is an English magazine. This ad is from 1948, and wants us to buy canned peas. Ugh. I frikkin hate peas. They smell like underpants and each one is a little plastic bag of mush that bursts when you bite it, spewing it's load of fecal paste all over your tongue. But, this was England shortly after WWII, and people were probably thankful for what they could get.
It's not like "processed" means anything. It could just mean the peas have been chosen for uniform size, and cleaned of stems and other unwanted materials. But people expect their food to seem like they're eating it right out of the ground, even when it's spent a few weeks in a can on a shelf. People are unreasonable.
My dad liked peas. He'd have them as an evening snack while watching TV. No bowl or heat required. He's crack open a can of peas and eat them with a fork, right out of the can, watching M*A*S*H. Yep. Dad was in the army. My guess is this is where he learned to stomach canned peas under the least appealing conditions.
The nutritional claims made in the ad are not convincing to me. I'd rather eat four times the volume in mashed potatoes. I'd rather eat seven times the peas' volume in carrots. Make me eat peas and you'll get three times the peas amount of vomit on your table. Put me through a war and half starve me for a few years and I may sing a different tune, but for now, that's my decision.