Like everything in Japan, weddings have rules and it is an industry.
Until recent years, hotels would have an extensive wedding team, the shrines publish every year a calendar of lucky and unlucky days where your marriage will ever be prosperous and happy or set to fail!
In the recent years, the market is shifting to wedding venues but is also shrinking as the demographics of Japan change. Remember we are in a superageing society and people no longer want children. Mechanically, we are not in a good place!
Being invited to a wedding can mean you are a colleague, a boss or a university friend. Parents must invite their colleagues, it came to a point where couples would marry abroad to limit the cost of those invitations and have a proper happy day