You must be kidding. Did you even read that article???
It confirm that you need 100k€ to deal with Vanguard Europe directly, that you get double taxation (USA tax then home country tax) on your returns, and you take all the risks on the currency exchange, and that's just the beginning of the article...
So, I'll repeat it again, the USA investments are NOT available in Europe and the equivalents are mostly non existent or sub-par.
But there's very little stopping Europeans from buying Vanguard funds or ETFs, so this is a cultural phenomenon, not because of any legal barriers.
http://jlcollinsnh.com/2014/01/27/stocks-part-xxi-investing-...