RE: Why isn't travel to work tax deducted...?

As an Uber and Lyft driver, most of my earnings are wiped out by the mileage deduction. But, as you state, you can do that as self-employed.

I think, at least in the US, that the mileage deduction can be claimed by your employer, if they choose, and they can reimburse you in part or in full. I've had jobs that reimburse for driving while on the job.

The rules here state that I need to be heading to a business destination to qualify for deduction. The commute, even if self-employed, to or from the office or place of business is not covered. The IRS considers commute as personal driving as you would have had to get to work in any way possible, making it a personal choice to drive.