That is an intretresting view.
I understand, and respect the sentiment.
However, in a co-worker dynamic, it makes sense everyone pays for what they order. I think they would feel guilty if you were buying them lunch.
If my co-worker payed for my lunch, I'd want to buy for them next time.
Putting a bunch of colleagues in an "I owe you" situation (intentional or not) probably isn't the best idea.
I think you could offer to cover tip for the table and be within reason.
If they were making more money than yourself, would you expect them to cover part of your bill? I think most men would say no, you pay for what you eat.
For a birthday or something, go ahead and push it a little more, but don't refuse when they return the favor (assuming they are decent people).
The fact they want to split the check is a big step from the steryotype of women expecting the man to cover the bill.
You're not their wallet, and if they treat you like it, run.