¿le o les?

[Nora]

I keep seeing constructions like this one in print:"Deberíamos enseñarle a las personas como trabajar." I am thinking that "le" represents the indirect object (personas) and should be plural, but it is not done that way in the Spanish-language paper I read. Why not?

[Spanish Teacher]

¡Hola!
You're right, it "should" be plural (enseñarles), but there is a strong tendency everywhere in the Spanish-speaking world to use "le" for "les" when the pronoun is redundant.
Saludos