The price of the share has to be adjusted at the dividend ex date to reflect the drop of value induced by the dividend payout. If not every holder of the share class benefited from it, then this is obviously unfair.
Now if you are talking about different share classes, then they would have to either be issued to current shareholders (e.g as rights issuance, in which case every shareholder could have them, long term or not), or publicly traded (same thing basically, everyone could have them, long term or not), or privately traded. In that last case, I would not really say this is "for long term investors", it's more a matter of private equity / politics / governance. Don't expect to enter that kind of deal unless you are a _big_ institutional investor.
General discussion of the concept in France. http://jpkoning.blogspot.com/2016/09/the-french-shareholder-...
> Despite ensuing controversy in the French legislature over the fairness of elevating one class of shareholder above the rest, the ability to provide prime de fidélité was enshrined in French law in 1994, with several limits.
So indeed they provide you with a different share class. What is amazing though is that they have what look like an automated process to convert your shares from public to registered (private with fidelity bonus).
Reselling these shares is not really explained in the page though. They seem to imply that your broker will swap them for regular shares that you can then sell on the market.