Yeah, they put the burden on the employer to make it easier for the IRS. If it comes out the employer's pocket the then the employer has an incentive to make sure the commuting expenses are legitimate. That prevents the IRS from having to audit a bunch of small deductions on their end. Also, in order to take advantage of most deductions, taxpayers will have to itemize. Since the large majority of taxpayers just take the standard deduction instead of itemizing, classifying it as a deduction would actually prevent the average taxpayer from taking advantage of the provision.

Here's the problem, in my opinion, with these sorts of measures. All of the congressional representatives that voted for this provision can stand up and say "Hey...look at me. I voted in support of cycling, the environment, etc."

Now, will it actually work?
Is it cost effective for employers to administer?
Is the amount large enough to make a difference for employees?
Can the average employee/employer understand the details of the provision or will they have to hire a CPA to figure it out?
Doesn't it just add an additional wrinkle to an already complex tax code?

These are all questions that our politicians can easily ignore and leave for someone else to figure out. In the meantime, they can be "on record" as supporting cycling, the environment, etc and use that as a selling point in their next election.