LONDON—”Payment for order flow,” a practice critics say has fueled bouts of frenzied retail share trading on Wall Street, should be banned in the European Union, France’s stock market regulator said on Thursday. In the United States, stockbrokers have touted for business among retail customers by offering zero commission services, with payment coming from sending the orders to a specific wholesale market maker for executing. Robert Ophele, chairman of France’s AMF securities watchdog, said the situation was even more complicated in the EU due to the lack of a single markets regulator. “I am strongly inclined to favor the clarity of a ban for payment for order flow,” Ophele told an event held by European markets industry body AFME. The EU is reviewing its securities market rules known as MiFID II with a view to making a series of tweaks in a bid to deepen its capital market now that …