They could. I envision a one time use token for each charity you give to. You give the charity the one time use token issues by the government, and they report your donation directly to the government.

Financial institutions and other companies already give the government a copy of the form they give you for self employment income and taxable financial transactions.

The states also report state taxes and property taxes(?).

This would cover most taxpayers. If you have anything more complicated you would have to add it. This would also make enforcement easier, it could for the most part be automated.