France, Germany, Sweden, Netherlands, Austria, Denmark, Finland, Luxembourg and Iceland all had them until recently. 15 European countries in total had them, now just four do.
Spain - but they have reduced it over the years
Norway - the government has stated they want to reduce and eventually eliminate it.
Belgium
Switzerland - it is a tiny percentage and crucially - it is hugely offset by the quality of life there.
Governments are not in the habit of reducing or removing taxes if they increase tax revenues.
I don't know how to get it through to you. They are not experts if they are getting it wrong. This 'expert' of yours says people don't leave if taxes are raised, but there are many countries around the world that prove that to be completely false.
What tax rate would i choose? I would have a flat rate on all income, say around 25% or whatever percentage would match the current tax receipts, for everyone. No loopholes, thresholds, or other get outs. What's fairer than the same rate for all?