I agree with the OP that eating 'on the go' is difficult. Going to a restaurant is not too bad as there are dishes you can have and add/subtract greens and carbs.
We travel up and down the M1 fairly regularly and previously would have a Maccy d's mcmuffin for breakfast

and usually stop and have a costa coffee latte and muffin further along. However that is now out of the question. So we have to work around it; we have breakfast before we leave , I do a plate of cold ham, eggs and cheese the night before as doing a fry up at 04:00 isn'y my idea of fun! We take with us a box with nuts an cheese and some fruit in. We had worked out that if we were 'desperate' we could have a mcmuffin but just remove the muffin bit. Service stations do now tend to sell salad boxes in the stores there now but you have to make sure you have a fork to eat it with! Latte's are history so it is a black coffee now.
Yesterday though we were out and decided to stop for lunch at the cafe in Waitrose. Nothing suitable at all. Lots of sandwiches, panini's, pastries, cakes and muffins. We thought we may have been able to get a 'breakfast' but it was either bacon or sausage in a bun. There was a sweet and sour chicken dish which we could have had without the rice but we didn't want a 'meal' and who knows how many carbs there would have been in the sauce anyway!
It is difficult to eat on the move so we tend to eat at home these days and just stop for coffee's. Now instead of having sweets in the car, we have nuts!!
I am not sure we can change the choices offered in cafe's. As an earlier poster said, they will be selling what the majority of customers want so doubt they would change too much.
On another point, I too couldn't have imagined not eating cereals, cake, potato etc but it is surprising how quickly you can get used to it. I should add I do not have diabetes, it is my husband, but I don't think it is fair for me to eat carbs whilst he doesn't so we eat identical food. I am conscious that I will have to be careful not to lose too much weight so I sometimes have a carby snack or meal when I am out with friends. In saying that I had some cake when I was out with a friend the other day and didn't really enjoy it - too sweet!