Numerous taxes are typically introduced (from my own experience) as a way of governments increasing taxes without generating a lot of negative attention - you don't often notice them (until you end up having to pay them). While there is justification for having several taxes to make sure you target the right areas (e.g. you may wish to have an inheritance tax to increase opportunity/prevent all the money just accumulating to a small group, or you may wish to tax particular goods which produce harmful effects like cigarettes), but that doesn't justify the whole range of taxes that there typically are. For example you can be taxed on the money you make from employment. Then your employer can also be taxed on that. Then you can be taxed when you save that money (on the interest), and then when you spend that money you can be taxed again. If you spent it on an item which you then sell later on for more than you paid, you can be taxed even more.

If all the taxes were condensed into just one or two, I expect the figure would be so high that it would cause an uproar, even though simplifying them into such a small amount would remove various loopholes, decrease compliance costs, and allow for a lower effective overall rate of tax. So ironically people's opposition to a high (visible) level of tax means they get taxed even more.

A flat rate tax could be given a high annual exemption to avoid the most severe effects of it on the poor people - it'd mean the poor would benefit, the rich would benefit, but the middle class would be the losers (since it'd be unlikely the gains from simplicity would be enough to offset the decreased income from a lower tax rate applied to the rich).

man we got some real winners getting great powerful positions in politics hey?! I guess it pays to be a slime

I definitely agree that some serious reform needs to happen to our current tax system, it is just too complicated, which tends to lead to loop holes being exploited by those who can afford to find them.  That said we don't need abrupt reform which is likely to shock and bother the average tax payer, you can't throw out the current tax system and switch to a flat tax overnight without a lot of uproar, however if you make slow subtle switches over a long period of time then you can move towards a more efficient system.

For example one quick and easy change is to get rid of one tax like tax on earned interest to encourage people saving money (also helps to fill banks balance sheets to enable them to lend more) and establish a very small federal sales tax on certain good and services.  Over time you slowly eliminate other taxes and moderatly increase that federal sales tax to ease people into the idea of paying a federal sales tax (or whatever you want to use as the flat tax).  One way to avoid impacting the extremely poor is issue some sort of card that can be used to exempt people from the federal sales tax which can be used like a credit card and effectivly amounts to your tax return.  Obviously this isn't a very well thought out system yet, but it's something to work from.

It'd create an uproar - you'd be taxing the poor to give to the rich, and encouraging people to cut back on spending and save instead (the last thing you want to do in a recession).

Wouldn't it be more straightforward to look at income tax rather than using a sales tax, and then complicating it to try and avoid such effects? Introducing such complications is why governments so rarely manage to actually simplify the tax system, even when they may want to, and instead make things worse than they were before.

That would be great, but apparently many rich folks don't pay taxes unless they get caught, example: recent cabinet appointees,