RBI vs run scored: two different baseball statistics
Why a hitter can drive in a run without scoring one, or score without an RBI.
An RBI is a credited contribution
MLB's glossary describes an RBI as credit in most cases where a plate appearance results in a run. A run scored belongs to the player who completes the bases. The same player need not receive both statistics on a play.
In a hypothetical single driving a runner home, the hitter can receive an RBI while the runner receives the run scored. That is not two team runs: the columns describe different contributions to one scoring play.
A hit is not always required
A bases-loaded walk or hit by pitch can produce an RBI. A batter can also receive one when making an out if a run scores, subject to the exceptions. RBIs are not simply the number of run-scoring hits.
MLB notes exceptions including a run scoring because of an error or a ground-ball double play. Do not assign the credit solely because a run appeared during the batter's plate appearance.
Keep individual totals out of the team sum
Adding RBIs to runs scored would count contributions again rather than reconstruct the scoreboard. A team's final run total is already the score, not a base number awaiting the addition of player credits.
ScoreZaap's team score and box-score statistics answer different questions. Wait for the official scoring attribution before describing a real play as an RBI. This guide uses a labelled hypothetical single, not invented commentary for a named game.