2 Kings 12:3 - Joseph Benson’s Commentary on the Old and New Testaments

But the high places were not taken away The people were so much and so strangely addicted to these private altars, (on which they sacrificed to the true God,) that the preceding kings, though men of riper years and greater power and courage than Jehoash, and firmly established on their thrones, were not able to remove them. And, therefore, it is not strange that Jehoiada could not now take them away, when the king was young, and not well settled in his kingdom, and when the people were more corrupt and disorderly through Athaliah's mal-administration.