Why does my employment expenses not reduce my income?

[TonyC11]

Because it is a non-refundable tax credit, not a deduction from income.

For most taxpayers, the only true deductions you will see are RRSP and RPP contributions.

In some cases you might have Union dues or deductions of income due to Pension splitting.

But in the majority of cases, you will possibly get tax credits, almost all non-refundable!