It may sound silly, but here's a few:
* extra customs checks, even if there is no customs rate
* different VAT procedures from the common market
* courier and postal services delivering strictly within the EU, or charging a premium for dealing with the barriers of delivering outside of it
Apart from that, anecdotally, even within the EU, we noticed that UK customers were strangely much less informed about SEPA bank transfers (between € accounts, within EFTA) than even non-EU EFTA members.
Apart from that, anecdotally, even within the EU, we noticed that UK customers were strangely much less informed about SEPA bank transfers (between € accounts, within EFTA) than even non-EU EFTA members.