@John *********
Indeed it might be very frustrating, but it is also logical.
With a visa you apply to be a guest in a country.
A country, just like most people wants to have the possibility to choose which guests it is allowing and which it does not allow.
There is not always a clear reason why a country does not want you as a guest.
A visa should not be compared with an entrance ticket you just buy, but more with an invitation to visit.