Is washing tomatoes, apples, oranges etc. with dish washing detergent normal? She's literally unmovable no matter how I tell her she still keeps doing it. I am freaked out.
Is it 'normal'?
No, it's somewhat germophobic behaviour.
Will it do you any harm?
No, so long as it's rinsed well. If you can't smell it or taste it, you'll be fine. It's just like leaving your dishes to drain rather than drying with a tea towel. Even if you can still smell or taste it, though gross, it's still not concentrated enough to worry about.