Why do we not hasten to say "Lā ilāha illā Allāh" (There is no god but Allah) when Allah is mentioned, and why do scholars not urge this, by analogy with hastening to send blessings upon the Prophet when he is mentioned?

When a Muslim hears the mention of Allah Almighty, he should glorify Him, praise Him, affirm His Oneness, or exalt Him by saying: "Subhanah" (Glorified be He), or "Ta'ala" (the Most High), or " "Tabaraka wa Ta'ala" (Blessed and Exalted be He), or "Azza wa Jall" (Mighty and Majestic), and similar expressions that convey veneration. This is prescribed, even if some fall short in it.