Why URL of deleted blog is not available for new blogs in Blogger

Blogger is undoubtedly the most used Blogger platform and over 80% of Blogger user uses .blogspot.com domain provided by Blogger for free and people love to have their desired blogspot address for their blogs.
But you aren't always lucky to get your desired domain, if the blog URL is already taken by other then you will see message saying 'Sorry, this page is not available', if you see this message than the possible reason could be that the address is being used by an other blogger user.
But when you check the URL you see that the blog has been removed ! The first question that pops up in one's mind is why the blog URL isn't available even if the blog with that URL has been removed ? What it exactly says is
Sorry, the blog at blogname.blogspot.com has been removed. This address is not available for new blogs.
And this is the page where you will see this message

What's reason ?

Have you tried deleting any of your blog on Blogger ? If you are familiar with the deletion process of blogger then it's easy for you to understand why sometimes blog address isn't available even if the is deleted or removed.
When you delete a blog on blogger the Blog will be still available for you to undelete it under 90 days after the deletion. For others your blog has been removed but you know that you can still undelete the blog with it's URL and that is the reason why blog address aren't available sometimes.

What to do now ?

There are couple of things you can do to get your favorite domain name for your blog. Using any of the tips below can help you get your preferred blogspot address.
Wait for 90 days : This is the easiest one, we know that blogspot can be undeleted before 90 days of it's deletion. Yup, you guessed right, you can wait for 90 days or not even 90, maybe it's the 89th day when you  tried for that domain and the next day it will be available. You can try for that domain every day and if it's over 90 days of deletion of the blog then it's URL will be available for new blogs, you can then choose the URL for your own blog.
Contact the blog owner : If you are impatience and want the domain without waiting and checking for the availability of the domain for 90 days then what you can do is contact the owner of deleted blog. Now you maybe thinking how it's possible to find out whose blog it is ? Google is just a click away, search Google for the blog address and if the blog owner ever participated any forums or commented on other blogs you can easily find their Blogger profile or email id through which you can contact him/her. Tell them to undelete the blog and transfer the controls of their blog to your account. If they are kind then you will get your desired blogspot address.
Buy a custom Domain : I recommend you using Custom domain for your blog, you can choose what TLD you want i.e if the domain you want isn't for .com then you have the option to choose other TLDs like myblog.net, myblog.org etc.
I hope you get helped with these tips and suggestion.