There are multiple questions and the accepted answer only addresses them partly:
Why was the North so slow to catch on? Why wasn't this tactic used
more frequently during the war? Was this technique used more widely in
1st question is partly adressed, but let's put apart the "mentality" thing which, especially in the USA of the Civil War, which had no big previous army so no previous "mentality", is not as strong as it is often said: People are not stupid and try to adopt what succeded against them.
Unionists could not copy fast Confederacy cavalry raids because they lacked horses and people knowing how to travel on horses for a long distance. But as soon as 1863, they had put their own cavalry forces in service as big units and used them against COnfederacy, with more and more success.
2nd question is based on false premises: cavalry raids were widely used when they could be effective: they were done between campaigns, when both enemies had no big forces to use against the raids. They were used as recons for enemy offensives.
3rd question addresses subsequent wars (in the world I suppose because USA did not know more wars): For Indian wars in the USA, yes cavalry raids were used but very differently: Often, Native forces were less numerous and could not assault successfully American railway station or military forts, as a raid of the Civil War would have done. The American used cavalry raids as retaliation (see Wounded Knee) or as tentative to confront Native warriors groups (see Custer at Little Big Horn).
In other wars, yes, cavalry raids were used: in colonial wars by the British and the French units, with little units. During 1870 war, it could not be used all the time because of the density of forces.