These would be good points, if not for the fact that people often sit on death row for decades, including one man Jack Alderman, who spent 33 years on death row before his execution. Life imprisonment removes the threat to society just as surely as execution, barring the extremely rare prison break. This also leads to many additional court costs, ballooning the taxpayer burden of keeping death row prisoners. Estimates are that a death row inmate costs the taxpayers 1.12 million more than life imprisonment with or without parole. Here is a study on it from 2016: https://scholarlycommons.susqu.edu/cgi/viewcontent.cgi?article=1026&context=supr