Whenever the government in the UK decides to charge for something, especially if it was previously free, it is in turn charged with "stealth taxation". I don't know about other countries, but I imagine that the politics are similar. There is often a good reason why the government wants to levy a charge, which often has nothing to do with its overall level of income. An example is the recent proposal to charge by the kilo for domestic refuse collection: the "polluter pays" principle is generally recognised as sound and "free" rubbish collection is increasingly expensive. But not everyone agrees:
Mother-of-five Mandy Price, who has just begun to recycle but still produces an average of nine bin liners of rubbish a week, said the assembly could not justify introducing such a policy in the wake of council tax rises.
She said: "You pay your council tax for the local authority to come and collect your rubbish, so why should we pay more?"
In other words, the charge is perceived primarily as just another source of revenue rather than an attempt to shift the costs onto the people who actually use the service the most. The government response is always to say that this is going to be offset by lower taxes elsewhere (in this case, council tax), but this makes a very unconvincing soundbite.
Gross Domestic Product is a standard way of measuring the overall economic activity in a nation or economic area, and the usual way of measuring the tax burden on an economy is the ratio of taxation to GDP. For instance, Reform points out that the US takes 26.4% of GDP as tax, whereas the UK takes 35.8%. Of course, these figures are almost useless for international comparison because they don't say what the tax pays for. In the UK most health care is paid for by the government out of general taxation whereas in the US it is mostly paid for privately by employer-funded health schemes that get a tax break. The NHS is funded out of taxation, and so is charged to the government's account, but a scheme partly funded by a tax reduction (as in the US) is not. If the US were to eliminate the tax break and subsidise these schemes directly instead then the basic nature of the system would not change one whit, but the proportion of US GDP taken in tax would increase. The US spends around 16% of GDP on health care (compared to about 8% in the UK). From an employer's point of view taxation and healthcare are both just costs of doing business, and the overall burden of general taxation and healthcare in the US is actually higher than in the UK. As always you get what you pay for, but a worrying amount of political debate seems to revolve around which ledger the payment is recorded in.
However one place where such figures would be useful (but never seem to be used) is in domestic political arguments. The Liberal Democrats used to have a policy of adding 1% to the rate of income tax in order to fund improved education. Meanwhile the Tories are struggling with a reputation for aggressive cost-cutting in public services in order to fund tax cuts, and the Labour government has been increasing taxes in order to spend more on public services (with notable lack of effect, but thats another issue).
What I would like to see is for each party to declare a target level of taxation as a percentage of GDP. That gets their macro-economic policy on taxation out in the open, without confusing it with a lot of micro-economic questions over how it is collected. Thats not to say that those micro-economic questions are unimportant, but they need to be separated from the macro-economic debate about the overall level of taxation.