I think that would be a great idea for them. Even if it was just a tiny tiny portion, like a crayon or something, enough to test it on your hood and see if it's really worth it.
But then again, let's be realistic, they're not selling a $2000 wax, they're selling a $200 wax and $1800 in name and exclusivity.
Once you use any decent wax, the return from stepping up gets lower and lower. Many people find it difficult to tell between a lower priced wax like M26, to something in a P21S, Wolfgang Fuzion, Dodo Supernatural, or one of these Zymols. The "gains" are no longer equal with the increase in price.
So the samples of Zymol that would be given out or sold might not show enough of a difference to a Dodo Supernatural or Souveran or something like that and keep someone from buying it based on their marketing. They get an edge by making people want it due to its hype and price, so very few people who buy a lifetime supply of it are going to say "it wasn't as good as I expected".