This is the case also for the UK, Europe, Canada and New Zealand. If you don't have "proof" that this money is legitimate and belongs to you, then it'll be seized.
There is no civil forfeiture as such in Europe. The UK and Ireland have a weaker version of the US situation but no other member of the European Union has it. What you are talking about (crossing a border with over a certain amount of money in cash without declaring it) is a completely separated topic that exists basically everywhere and is not a problem because it is very clear what you should and should not do (do not cross a border with thousands of dollars/euros in cash without declaring it to customs).