One account for all Google is true?

One account for All Google is not 100% true?

It looks like with one account in Google is for all Google, but here you can find out is not 100% true.

1- I use my Google account to access my https://www.google.com/webmasters/tools, where I set up the domain camssay.com and camssay.co.uk. I have verified them on webmasters website. Check it on the next images:

camssay.com verified on Google webmaster tools

camssay.com verified on Google webmaster tools

camssay.co.uk verified on Google webmaster tools

camssay.co.uk verified on Google webmaster tools

2- Once I tried to create an API by using the console of developers(https://console.developers.google.com), using the same account.
When I have added my project, on the “Credentials”. Using the option “Domain verification” by adding my sames domains names(camssay.com and camssay.co.uk)
add domain again

Google asks again to verify the same domain:
camssay.com verify again

Conclusion:
I believe to be like one account for all Google, should not ask two times for a verification(like admin in both side). If I have verified my domain name using the same Google account on the Google webmaster tools, Google should not ask again to verify the same domain on Console developers. The first verification was with Google not on Yahoo, Baidu, Bing or Yaindex, so is not sense to ask again.