The buyback event itself is not taxable. For dividends, the recipient must still pay taxes even if they are reinvested (as is common) and this cash flow and tax burden is unwelcome for larger investors.
In the Netherlands, appreciation is immediately taxable for individuals, but not for corporations.
I presume you don't send a cheque off for €1.36 at the end of the day, (or receive a cheque back after 8 months)
Of course this state of affairs relies on companies not all jumping to stock buybacks, or else the treasury will find some new way of getting their pound of flesh