General infrastructure planning tends to be decided on long term efficiency as its not a day to day political issue.

What planet do you live on?

Possibly, but the dead don't tend to pay taxes,

Neither do retirees. Furthermore, anyone with a chronic illness, or anyone who isn't rich for that matter, is a net drain on finances. But this analysis implicitly assumes that governments are run to maximize revenue which is blatantly false, at best some department might have a fixed budget and might try to figure out how to spend it to maximize some metric.

Interestingly the NHS spends a lot of money on people in the final stages of their lives, while they could save a lot money by legalising or enforcing euthanasia

Being that explicit about it would loose them votes; however, at the margin such things do happen.