It’s not an either/or situation. We both need more regulation and harmonisation regarding tax evasion and tax dodging both inside and outside the EU and less regulation when it comes to starting businesses.
To steal from other EU members is no competition it's just unethical. Small countries can live just by cashing a small part of the money that is rightly owned by countries with more population. That needs to be fixed.
Also obviously the EU can put in place any kind of controls it deems necessary on the common market. It’s sovereign in this matter after all and tax dumping is mostly helping foreign-based multinational corporations.