But in verbal English I can say Why not we stick to one standard?,
people will understand me.
Yes, people will understand you (which is evident in that we answered your query

), but it is not correct English grammar, and it is not how native English speakers would say it.
Republican knives out for their party's health bill
knives out = means what?
To have your "knives out" means that you are ready to attack it, criticise it, cut it to pieces, destroy it, be unpleasant about it etc.
A manhunt is under way in Germany after a man allegedly stabbed a nine-year-old neighbour to death and uploaded a video boasting of his deed to the dark web.
dark web = criminal web? Opposite is bright web?
The dark web is a section of the World Wide Web that requires special software to access, where anonymity is paramount, where things can be discussed, bought and sold, mostly without fear of being snooped on by governments and law enforcement. It is therefore rife with illegal activity, and popular with criminals, terrorists and the like.
Presumably the "dark" is because it is effectively hidden from view.
tit for tat
I noticed she didn't send me a card - I think it was tit for tat because I forgot her birthday last year.
Why tit why tat?
i used to think this came from "this for that" (as in: you give me this, I give you that) but is actually from "tip for tap" meaning an exchange of blows. In your example, not sending a card was the retaliatory action for forgetting her birthday.
It is basically a case of you hit someone, they hit you back; you get hit, you hit back, with the implication that the exchanges are of roughly equal magnitude.