Ernesto Valverde says it is "absurd" that La Liga officials are not backed up by technology after Luis Suarez appeared to be denied a legitimate goal in Sunday's romp over Deportivo La Coruna.
Suarez scored twice as league leaders Barca hammered Depor 4-0 at Camp Nou, but was denied a hat-trick after seeing an incredible 'rabona' finish from a narrow angle ruled not to have crossed the line late in the first half.
Replays seemed to justify Suarez's mystified response to a goal not being given.
La Liga is the only one of Europe's major leagues not to use goal-line technology or Video Assistant Referees (VAR) and Valverde was equally baffled at the lack of assistance given to officials in Spain's top flight.
He told reporters: "I didn't see it, but with the help of technology, you'll know if the ball has gone in or not, regardless of whether the VAR is used or not.
"I don't know why it is not used in La Liga.
"The equipment must be very expensive, but it's absurd that we don't have it. We're late and it shows."
The Royal Spanish Football Federation last month confirmed VAR technology will be implemented in La Liga from the start of next season.
That, though, is of little consolation to Barca, who have already seen Lionel Messi denied a perfectly good goal this term during a top-of-the-table clash with Valencia.
The Argentine forward saw an effort fumbled by Los Che goalkeeper Neto in November, but none of the officials in charge of the contest spotted that the ball had crossed the line.