I might be able to offer some insight here - Carthage, as a state, was unduly burdened and then eradicated in a, quite frankly, shameful manner, but Carthaginians were ethnic Punics. Rome, after Carthage itself was destroyed, allowed the Punics of North Africa to continue practicing their culture, religion, and language without interference. Hell, in the future, Emperor Septimius Severus was part Punic, even, and spoke Latin with a Punic accent! So it’s really just a matter of the Roman Republic holding an irrational grudge against a single city.

As for the druids, they were wiped out, specifically, because Rome was trying to keep the Gauls and Britons from revolting as much as they could. Druids were a priestly caste, but also a caste of leaders that people could rally around. Other Gallic and Briton religious practices survived unmolested.

Both were also accused of human sacrifice by the Romans (who considered such practices both immoral and an offense to the gods), and whether that was true is a whole can of worms waiting to be opened. “Not today, Satan” I say!