Never the Twain shall meet, thank goodness! We should celebrate and enjoy our differences because, unfortunately/fortunately, they can never have that party!
Nothing. Coin collectors like the circular bits of metal. These other people like a square piece of plastic with an arbitrary number printed on it. Two completely different sets of people. Perhaps some enterprising individual could separate the two camps fully by just issuing bits of plastic without anything in them!! 😉
Most guesses of surviving numbers are underestimated, relying to a large extent on personal experience, which is a bit hit and miss as you can't pick up everything. There is no central database of coins, so you will almost always revise numbers upwards. The only exception to this is likely to be for cases of mis-identification where one type will reduce and another increase. Patterns and proofs are a bit more quantifiable.
Additional examples from known dies can appear at any time, just as new die pairs appear on a regular basis. We only have a fraction of the story.
Yes, but they tend to get upset when you tell them. When I pointed out to someone on CoinTalk that 'I collect coins, while you collect opinions', he got a bit miffed. Diplomacy has never been my strong point, so if someone could enlighten me on how to call a spade a spade without offending, I would like to know.