From EU Green Paper on VAT:
"The current collection model brings with it a VAT Gap due to e.g. VAT fraud, insolvencies, mistakes by the taxable persons in the VAT return and VAT avoidance schemes. Desk research shows that the VAT Gap for 2009 can be cautiously estimated at 6,9% of GDP and 12% of total VAT liability in the EU-27. This means that, in the EU-27, a total of EUR 118,8 billion has according to those estimates not been collected by the tax authorities in 2009."
And it is our money - taxpayer's money. So we should see to it that it is collected (taxes can then be lowered) and that the collection is made automatic - cost efficient for enterprises and tax authorities:
"The complexity in the VAT rules results in administrative burdens for businesses. Dealing with VAT accounts for almost 60% of the total burden measured for 13 priority areas identified under the Better Regulation Agenda. According to business, this is making the EU a less attractive place to invest."