Obviously we can all pretty much agree that "brilliant uncirculated" tends to refer to approximately MS60 - 62, generally speaking. However, considering coins marketed and sold as "BU rolls of x number of coins" are ones that have never been placed in circulation, is it possible to find a higher grade coin, say MS64 or 65 included in a "BU roll" or perhaps the popular 3-coin Morgan silver dollar year sets?
Actually, we can agree on nothing of the sort. MS60-62 are very unusual grades EXCEPT for the very biggest and heaviest coins. For example, I recently bought a plastic tube full of MS 1970-S cents at a show for 3 bucks. I went through them and one of the UGLIER coins in the tube was a small date variety. It graded at NGC as MS66RED. There HAVE TO BE many non-small date MS67's or better in there. Morgans are a different story. They are heavy and have clanged around against one another quite a bit. It is relatively ordinary for a modern coin from an uncirculated set to grade MS68. Want an example? Check out a typical half dollar in a 2017 Uncirculated Set from the Mint. They are MAGNIFICENT this year.
Of course it is, but there are no guarantees. With older and/or possibly more valuable rolls, it is wise to remember that there's a possibility they may have been searched, and this includes those appearing to be machine rolled. With newer or more plentiful rolls it's not much of a concern, and coins in said range usually aren't worth that much. Perhaps it would be helpful if you were to clarify exactly what types of coins you're asking about. The same with sets... of course coins in your cited range can be found, but again there are no guarantees, and you'd be wise to remember that you're not the first person to have thought of this; picking sets is a fairly common practice. What exactly are you talking about?
