Verb conjugation is not tested in GMAT as all GMAT SC problems are written in third person.
Verb conjugation is applicable only for first and second person.
consider this :
I go ---
you go : here I and you is a first and second person pronoun respectively. But when we use third person pronoun, the standard rule of subject - verb agreement exists.
"she go" -- wrong --- it should be "she goes".
"You people" should be followed by a plural base verb - as its in second person
you people go.
you people seem to be...
You may refer this for more details :
https://www.eslgold.com/grammar/subject_ ... ement.html
In GMAT, the standard rule of S-V agreement is followed as all sentences are written in third person.
Hope this helps !!