In Jacob 1:15, the context is the depravity of the Nephites after the death of their first ruler, Nephi I. Having or even desiring concubines in the way of David and his son Solomon is an example of their falling from grace, as they
began to grow hard in their hearts, and indulge themselves somewhat [sic!] in wicked practicesJacob then (Chapter 2) speaks out about the evils caused by the lust for riches, which finds expression in the Nephites hunting after gold, silver, and other precious ores (v12), which makes them haughty in garment and bearing. But pride is not the only target of Jacob's remonstrations; the other is the chastity of women perverting practice of concubines (v27f), which is an abomination to the Lord, even back when David and Solomon were doing so (v23f). And in Jacob's words, the Lord is responding to the abject misery of the daughters of the Nephites, who are saddened by the practice of concubinage (vv.31-34). (The word tenderness, that Jacob uses here, occurs in the KJV only in Dtn 28, when describing the horrible cannibalisms of the besieged city; in the OT, tender is used for young animals and sons, or fresh vegetation, and the soft heart; the combination of "tender and delicate" applied to a female occurs only in Isa 47:1, when describing Babylon figuratively as the daughter of Chaldaeans. In the NT, mercy is tender, as is the fig tree in the Synoptics.)
Jacob uses the Lamanites (Chapter 3) as a positive example, because with all their filth and curses, they only know monogamy (v5), and thus put the Nephites to shame.
In Mosiah 11, it is the wicked King Noah, who takes over from his father Zeniff, who taxes his people heavily at 20%, especially the gold and the silver, and uses this money to build fabulous buildings, and to have concubines, just as his priests do, and to become a wine bibber and make his people into alcoholics.
In Ether 10, the situation is similar, where the wicked king Riplakish taxes his people, builds tall buildings, and has concubines (v5).
The evil of taxation occurs in the OT for King Jehoiakim (2 Kg 23:35), who raised taxes on gold and silver and give that to Pharaohnechoh (Pharaoh Necho II), who had killed Josiah at the battle of Megiddo and was requiring tribute (after the three-month intermezzo of King Jehoahaz). Jehoiakim did not do what was right before the Lord either.