[Texas] Working 8-10 hour shifts with no lunch. Should I be given one?

(Using a throwaway) As title states been with my employer for going on 5 years here in Texas. I have always been part time but I work usually work 8-10 (sometimes ever 12) hour shifts(I work practical full time). We usually have to ask for a break and sometimes are only limited to one 30 minute on the clock break. And no lunch breaks.

It's usually "oh we can't cover you for that long, we are really busy." Excuse. I've been working shifts like these for going on 4 years, one co worker for 5 years and another for 8+ years.

my question is. Is it legal to work long hours in Texas without being given a lunch? Anything I can do to help improve the situation.i found a full time job elsewhere so I plan on leaving within the month but I want to maybe try and help my co-workers.

Edit: this is just an issue in the department we work at. Every other department in the store doesn't have any issues with giving the employee's its lunch hours.