In business, few things are more challenging these days than running a profitable local restaurant. National consolidation of banks means there are few lenders willing to make loans to local restaurants. The best locations are controlled by publicly traded real estate trusts interested in renting only to national chains willing to pay the highest rents. The three big credit card companies skim 3 percent right off the top of every check. And if you think that takeout order will get restaurants through the pandemic slump, think again: The four big order-and-delivery apps capture anywhere from 15 to 40 percent of every bill.