Short answer: Lobbyists. Basically, the Intuits, H.R. Blocks, Jackson-Hewetts, et al., stand to lose a large chunk of their revenues if the IRS did everyone's

Short answer: Lobbyists. Basically, the Intuits, H.R. Blocks, Jackson-Hewetts, et al., stand to lose a large chunk of their revenues if the IRS did everyone's taxes for them. Additionally, those in power, or with enough influence over those with power, do not want to fund the IRS to have easy visibility into all of those possible revenue streams in an easily correlated manner.