"Lobbying" and "campaign contributions", aka paying congresspeople aka straight up corruption but you can't use the C word in US politics.
H&R Block and Intuit have been greasing palms for years to keep the agreement in place and encode it in law: https://www.propublica.org/article/congress-is-about-to-ban-...
> Those efforts have been fueled by hefty lobbying spending and campaign contributions by the industry. Intuit and H&R Block last year poured a combined $6.6 million into lobbying related to the IRS filing deal and other issues. Neal, who became Ways and Means chair this year after Democrats took control of the House, received $16,000 in contributions from Intuit and H&R Block in the last two election cycles.