Vehicle automation and smartphone app-based ride-splitting are commonly discussed topics in the transportation literature. While these technologies have been examined for their role in transportation decarbonization through simulation study, the motivation for such work is rarely made explicit. In this commentary, we provide a motivation for research in this area based on our own simulation research, as well as land use and vehicle operational factors. Specifically, land use factors such as density and the speed of its adjustment make traditional transit operations using large vehicles cost-prohibitive in most U.S. communities (and many other communities around the world). Automation and ride-splitting technologies may offer digitized transportation solutions that can match vehicle size to local land development density and passenger demand. In addition, we highlight a difference in the supply-demand relationship for freight transportation that causes additional challenges for decarbonizing that sector. Finally, we emphasize that fleet ownership is key to ensuring timely vehicle fleet turnover as safer and more efficient technologies enter the market.