ttk Label backgrounds work fine on Windows and, possibly, Linux (Serhiy?), and even, possibly with tcl/tk 8.6 on macOS (Ned?).  tk 8.6 for macOS has gotten several bug fixes.  C.D., please download and try out the python.org 3.7.0b3 macOS installer.  It included and will install for Python's use the current tcl/tk 8.6.x bugfix release.

import tkinter as tk
from tkinter import ttk
r = tk.Tk()
l = ttk.Label(r, text='colored label', background='red')
l.pack()
r.mainloop()  # if not in IDLE

We obviously should not remove something that works as intended on some systems.