This is not true in many industries, due to supranational regulation. MAT insurance (a huge financial product the UK exports to the EU) is exempt from this rule due to WTO regulation.
Furthermore, 'main base of operation' is pretty vague, and I don't believe it accurately reflects EU requirements. A subsidiary can be based in an EU country and provide you with all the access you would like. This isn't an option for smaller companies, but for larger ones its just an extra cost.
Furthermore, 'main base of operation' is pretty vague, and I don't believe it accurately reflects EU requirements. A subsidiary can be based in an EU country and provide you with all the access you would like. This isn't an option for smaller companies, but for larger ones its just an extra cost.