Is it common that funds charge the startup investee a fee to cover for your due diligence costs?

The VC charges for their own deal legal fees the startup., up to a cap.....? Why is that? The startup needs to pay legal fees to their own legal counsel/outside attorneys...why would the startup have to pay the legal fees of the VC fund as well (ok, subject to a cap)? What is the logic we penalize the startup in such an unfair way....legal deal fees for the VC should be paid out of the Operating Expenses for the fund, which are essentially paid for by the LPs (w potential to recoup these funds, if there is a Management Recycling Fee that is invested well and returns well)

Startups typically want to control their cap-table so they will have their law firm do a lot of this work regardless. With respect to it being 'fair' one could make a pretty strong counter argument that it's unfair to the LP that their money was used for this expense instead of being deployed into a company. Every fund expense is an opportunity cost.