Looks like ozone(pollution) damage from stagnant,polluted air. I'm having the same problem with my garden that is close to the house/porch ell. I plan to try disturbing the air with oscillating fans on the porch and see if it prevents the f ozone and sulphuric pollution from settling on my affected crop plants. It also seems to be at its worst in humid climates with excess rainfall as we are having this year.
Once affected , the leaf eventually dies but tomatoes can be cut back and regrow/resprout and fruit normally. This is
only practical in small scale gardens.

Thanks for the idea, Dottie. I would be really suprised if it was indeed polluted air because I live in a small town with pretty clean air. The garden is in our backyard, not too far away from the house, but as far as I'm aware there aren't too many toxic airs coming out of our place - at least during the summer when there aren't any stoves or fireplaces burning. Do you think this could be a thrip infestation? I've noticed that only the lower half of the plant has foliage that is looking this way. The top half is beautiful.

Doubt it's thrips. Could be leafhopper.

Is it possible to post larger images so we can see more detail?

It seems like it could definitely be leafhoppers. I heard at the local nursery the other day that lots of customers are complaining about them, as we've had a hot summer. I inspected the tomato plants more carefully today, and some of them have this speckled damage only on the lower half of plant, and others have it on 3/4 of plant from the bottom up. Would a spinosad spray do anything to prevent their drinking?

Another close up.

Yes, leafhoppers.

If damage is only on lower leaves, perhaps they're done & gone.