In jury selection each side gets a set number of potential jurors they can remove for whatever reason (this is not entirely true there are some limits). Arizona has apparently removed this because it might impact jury decisions on the racial side of things. There are some studies that support this although a clinical study versus the real world has a number of problems and I suspect the government wouldn’t be favoring this if it didn’t look like it would result in more convictions overall. (Its not fixing the problem if more innocent people are getting convicted in a more diverse way when the goal should be that no innocent person gets convicted).
There are times I know a potential juror has it in for my client at the get go, but there is nothing in the way they answer that would allow me to strike them for cause.