Learn Spanish (Latin America): Se notifican las infracciones graves al guardia. - Serious infractions are notified to the guard.

Because this sentence uses the reflexive passive (pasiva refleja). In this structure, the thing being acted upon—in this case, las infracciones graves—acts as the grammatical subject. Since infracciones is plural, the verb must also be plural (notifican). The guard (el guardia) is simply the indirect object receiving the information.

Could I say "Las infracciones graves son notificadas al guardia" instead?

Yes, that is grammatically correct and uses the standard passive voice. However, in both spoken and written Spanish, the reflexive passive with se is much more common and sounds more natural when stating general facts or rules without specifying who performs the action.

Why does the verb (se notifican) come before the subject (las infracciones graves)?

In Spanish, the subject frequently comes after the verb, especially in reflexive passive sentences. Starting the sentence with Se notifican emphasizes the action being done rather than the things themselves. You could totally say Las infracciones graves se notifican al guardia, but putting the verb first is very natural for formal or administrative statements.

Shouldn't there be an indirect object pronoun "le" here, making it "Se le notifican... al guardia"?