Why do we pray Zuhr and ‘Asr silently?

Why do we recite zuhr and asr prayer in low voice when it is clearly
mentioned in the quran the following ?.
Praise be to Allaah.
It was decreed that recitation in Zuhr and 'Asr should be done
silently because the time of these prayers is during the day, and at
that time a person's mind may be preoccupied with a lot of thoughts,
as he is busy with his work or trade or manufacturing. If the
recitation were to be done out loud, his mind would be distracted and
he would not listen attentively to the imam's recitation; he would not
listen to it or devote his attention to it; rather other things would
come to mind and distract him. So he was commanded to recite to
himself so that his recitation will make him think and ponder. It is
well known that if people pray in congregation for Zuhr or 'Asr
prayer, they should not recite out loud, because then they would
distract one another. So both the imam and the one who is praying
behind him are enjoined to recite silently. But with regard to the
prayers thatare offered during the night, in most cases people are
free from distractions so the imam is enjoined to recite out loud, so
that others may benefit from his recitation.
With regard to the verse which you mention, it applies only to qiyaam
al-layl and tahajjud. If a person is praying and there are people
around him who are listening to his recitation and others who are
asleep, then he should not recite so loudly as not to disturb those
who are sleeping orso quietly as to cause those who are listening
tohim to miss out on any benefit; rather he should recite at a
moderate volume, enough to be heard but not so loud as to disturb
those who are asleep. It also states in theverse that the Messenger
(blessings and peace of Allah be upon him) used to recite out loud and
the mushrikeen heard him and reviled the Qur'aan and the one who had
bought it, so he was forbidden to recite out loud and he began to
recite silently, but then the members of his household and those
whowere listening to him missed out on the benefit,so he was enjoined
to recite at a moderate volume.
Shaykh 'Abd-Allah ibn Jibreen (may Allah have mercy on him).