What are the problems encountered in any strict application of benefits-received and ability-to-pay principles of taxation?

What will be an ideal response?

Taxation based on benefits received will result in low-income people being excluded from some benefits because they cannot afford to pay the tax or fee for the public service. For example, charging a large fee to the users of public libraries rather than fund them out of general tax revenues would be an example of a benefits received basis for taxation. This tax or fee might prevent low-income groups from using the library. It is hard to separate the social from private benefits in such a case.
However, problems can also arise in strict application of ability-to-pay taxation. A strict application of this principle would mean no taxes that were not based on income or wealth. It would mean that those who were “able to pay” (however defined) would pay taxes for everyone else regardless of benefits received. Thus, only high-income users of highways, for example, would have to pay gasoline taxes. If substantial groups of individuals received public benefits of one kind or another without being responsible for payment of taxes to support them, it would encourage wasteful use of public goods. It would also discourage work and investment to raise income to the point where one was “able to pay taxes.” That is hardly an incentive to work or expand income and output.