The present perfect tense is used in the sentence below but here and here, they do not use the present perfect. Can we use present perfect simple tense in conditional sentences like the sentence below? If so, what is difference between has finished and finishes?
Unless a probationary employee has successfully finished the training, he cannot be considered a full employee and be assigned to one of the teams.
In conditionals like this, there is no difference between using finishes and has finished. You can use either of them and there is no semantic difference whatsoever. Which one you choose is a matter of taste.
Personally, has finished sounds better to me though.