Now, this is a proper royal Birthday celebration. I wish the British royals put on a proper celebration like this. I like it.
Why is there a constant need to belittle the way that the British do things?
The British do understated in many ways and then they do the grand coronations that they others don't do any more.
Different countries, different cultures and different ways of doing things.
That diversity is great in my opinion as it also reflects the ways that the different countries have developed and what is important to them.
To the British - individual celebrations such as birthdays are private events not public ones - that is their way and should be respected. They also do weddings differently believing strongly that there should be 'private' events as well as times to share with the public and a birthday party is a private events, as is a wedding reception but the church service to celebrate things is a public event. We will probably see that later in the year with the 70th wedding anniversary church service (assuming one is held either in the Abbey or at St Georges - given Philip's retirement it may be at Windsor).
Yes, Sophie is married to the Queen's son, but Catherine is actually the third lady of the land because she's married to the second in line to the throne. She's the most senior royal next to The Queen and Camilla.
Now perhaps the most senior royals will be sent to these events now that things are changing up in the fall.
You are confusing line of succession with precedence.
Precedence places ALL the sons of the monarch ahead of any grandsons and so Sophie is the fourth lady in the land ahead of Kate.
Kate is fifth.
The Queen, Camilla (as the wife of the heir apparent), Anne (a daughter of the monarch), Sophie (wife of a son of the monarch), Kate (wife of the elder son of the Prince of Wales).