Why is どうせやるなら more standard than どうせやったら?


I was working through the N3 完全マスター textbook and there is an example that says
「どうせ ____、面白い仕事がしたい。」The correct answer is やるなら, but another option was やったら.

At first, I thought maybe the reason why やったら is wrong is because たら requires
the first clause to happen first. It doesn't make sense to want to do an
interesting job after you've already started the job. But, you can say
「美味しいだったら、私も食べたい。」The first clause here is not a sequential event - it was
always delicious or it never was.

Also, upon asking friends, they said どうせやったら is possible, but it sounds like a
dialect. So what makes it sound "improper"?




(I originally started writing this as a comment)

なら feels to me like 'if you're going to do it', while たら feels like 'if you do
this, then'. The difference is slight between なら and だったら for nouns, of
course, but with verbs like this:

「どうせやるなら」 is 'if you're going to do it anyway' while 「どうせやったら」 just sounds
wrong to my ear, unless it's part of a longer sentence where どうせ isn't
directly modifying やる.

やるならやれ - 'if you're going to do it, do it'. やったらやれ - makes no sense. 'Once you
do it, do it' (you've already done it).

And as I said the difference is much smaller with nouns and adjectives
compared to verbs. I'm guessing because they need なる to reflect a _change_.

