[trinix912]

Each EU member state has their own stock market and you often can't trade the stocks from one country through the stock exchange in another. This means that if you want to offer EU-wide stock options, you either have to convince everyone to fly to your country and register at your country's stock exchange (which few will bother doing), or go through the process of filing and managing stocks of your company at 20+ different stock exchanges.

It's one of the things that have been recently brought up again in the EU parliament, but getting everyone to agree on a common stock market is not going to be easy.