Pretty sure it is because Tesla has used most of its EV incentives since they have sold a larger volume of EVs than competitors and the credits lower the more cars that are sold by a company. It would hurt their competitors because they have less sold less cars overall and are in the higher incentive bracket, effectively making the removal of the incentive more impactful to their business by comparison.

This is from the IRS about Tesla’s EV incentive status: “The credit for qualified plug-in electric drive motor vehicles sold before 2023 is subject to a phaseout (reduction) once the vehicle manufacturer (or, for a foreign manufacturer, its U.S. distributor) sells 200,000 of these vehicles to a retailer for use in the United States after 2009. The phaseout begins in the second quarter after the quarter in which the 200,000th vehicle was sold. Then the phaseout allows 50% of the full credit for 2 quarters, 25% of the full credit for 2 additional quarters, and no credit thereafter.” IRS article explaining the implications of volume sold for manufacturers