Explicit is better than implicit. The first line isnt a string, it's a collection of bytes, guessing that it's utf8 is not the right thing to do.
The encode (or is it decode? I always forget) defaults to utf8, which is what you should be using.
It helps me to think encrypt for encode (convert to bytes) and decrypt for decode (convert to text).
I'm not sure why this example is interesting. You can write:
print('I DONT WANT TO add "UTF-8" everywhere!!')
And get the same result. Or if you really want to start with bytes:
print(b'some string'.decode())
print(str(b'I DONT WANT TO add "UTF-8" everywhere!!','UTF-8'))
not quite default!