Yes money market accounts are taxed and so you do report and pay taxes on income you get from the money market account.
A money market account earns interest which is your income from the money market account.
The amount of interest or money that you earn from the money market account must be reported to the IRS on your income taxes.
Then if you earn enough money through the money market account you are taxed accordingly to the amount of income you make.
If you don't earn enough money through interest from the money market account then you won't pay taxes on that income.
But if you earn enough money to be taxed then you will be taxed and need to pay taxes on that income earned.