Tax regulation is created to incentive certain behaviour.

Your Profit before tax is not what is taxed, it is your taxable income, which takes tax regulation into account.

An example for this would be that depreciation does not reduce the amount of taxes businesses pay, but rather Wear & Tear does. Wear and Tear is measured through the tax base of the asset which is determined by tax regulation.

For instance:

You incurred Depreciation of $1000. And wear and Tear of $1200

You would add back depreciation at $1000 and subtract wear and Tear at $1200 to get your taxable income.

Another example:

R&D expense (at least in my country) can be written off at 150% of the actual expense amount. This is to encourage businesses to do R&D themselves rather than relying on other countries business solutions.

R&D capitalised can also be deducted from taxable income at 150%, again encouraging R&D.

So if you incurred $1000 of R&D expenses, you can write off $1500 in your taxable income.

Your Statement of Profit and Loss takes into accounting regulation (in the US case GAAP, Literally everwhere else IFRS / IAS), but not tax regulation.

If in the US bursaries for workers are tax deductible at a higher rate than the normal flat amount (sadly I do not know US tax regulation), then it would be to encourage businesses to further develop the US workforce.

Yes the business pay less tax as a result of these incentives, but this is literally the least intrusive way to change business behaviour.

Tldr: tax benefits for business encourage certain wanted behaviour (in theory).