If so, the veggies are stressed. Perhaps too dry? Or at the end of their life span?

Insecticidal soap, repeated as the label directs, works and will be safe for edibles.

Spider Mites are more of a problem during hot, dry weather, or if pesticides, including Insecticidal Soaps, areused because those will kill off the predators of Spider Mites. During hot, dry weather the Spider Mites feed more voraciously which causes them to mater more often which builds up larger populations. Raising the humidity round the affected plants can help reduce populations, just misting with plain water helps.

Here is a link that might be useful: About Spider Mites

It was said "Raising the humidity round the affected plants can help reduce populations, just misting with plain water helps."

Yes. in other words, the plants are stressed because of low humidity, etc. The above activities help minimize such stress a bit.

The amount of soil water, especially too little, also contributes to spider mite infestations. because the plants are stressed.

Every four days I use a strong but coarse spray of water from the hose (nozzle) upward from the lower parts of the plant so as to wash the underside of the leaves (which is where the buggers like to stay). This method reduces the population of freshly hatched and adult mites since they can reproduce in four days. I have found that, on my tomatoes, three or four thorough repeats will almost eliminate them. Works good for aphids as well. No pesticide products needed, soaps or miticides.
hortster