The conventional wisdom in the TDM arena is that incentives are good as well as necessary. We spend quite a bit of time coming up with new ways to provide incentives to help commuters find a different way of getting to and from work.
And, the field is not too hot on disincentives although there will always be advocates for pushing on that approach.
There is old evidence that making the commute a completely level playing field (i.e. no free parking, no transit passes, no discounts for carpools, no subsidies for vanpools ... in an area where parking comes with a cost) yields about the same drive alone rate as does providing incentives for ridesharing and transit. The "old" ARCO vs. Bank of America example is the prime candidate for this example.
Another argument about offering incentives is that if the incentives stop, commuters go back to however they were commuting before.
Give-aways, raffles, drawings, and promotions are frequently used and are regularly criticized for leading to "higher numbers" but not much real result. Effectiveness depends on who was recruited, what information was provided, and many other factors.
The question of this blog: Do you advocate the provision of incentives to cause a reduction in drive alone commuting? Why or why not? The question and answer may seem obvious but after talking with many states, MPOs, local governments, and others around the country, the issue is not universally obvious.
What is your best argument (either way)?