The National Transportation Safety Board wants children to have their own seats and be belted in on airplanes.
The FAA has historically rejected this because higher priced airline travel (buying a baby their own seat) discourages relatively safe air travel in favor of less safe highway travel. In other words, on net a reduction in safety (more baby deaths).
The NTSB disputes this analysis, arguing that families don’t get into accidents on the road at the same rate as teenagers and drunks. (Although my understanding of ‘alcohol-related fatalities’ in NTSB statistics is a blood alcohol content of 0.01… even a pilot could fly the plane at that level provided they also meet the length of time since last drink requirements, if I recall correctly.)
And even if true, the 1000 or so highway death a year of young children still must dwarf the risk of injury to a child on a lap.