Lawmakers have put less thought into other, more expensive projects over the years. After President Trump requested $5.7 billion to fund the border wall he campaigned on in 2016, Democrats have dug in, refusing to appropriate the funds that the administration says are needed to better manage the flow of immigration across the southern border. Democrats are not traditionally known for their fiscal rectitude but are being particularly parsimonious over what ultimately amounts to a very small percentage of the federal budget. (In 2018, the feds spent $4.173 trillion overall, meaning the border wall would amount to just 1/10th of...