Were all Shudra untouchables? Let alone scriptures, analyze social system only. The major jatis (it was like guild before caste system forcefully imposed by the British) of Shudras in northern India are Chamar, Kumhar, Teli, Kahar, Nai, Khatik, Luhar, Badhayi, Thathera, Dhobi, Mallah, etc.
Every Jati is a community of people having the same profession. Even till late 90s, barter system was prevalent in the villages. The need of money was minimal. Jatis were depened upon each other for various needs. And the mode of payment was service or goods depending upon the profession of Jati. Luhar (blacksmith) and Nai (barber) did not pay each other in money. Nai took care of Luhar’s hair and in return luhar mended Nai’s instruments.
The clients were fixed. For example, if there are three Nai (Barber) families in the village they will devide the whole village equally (To make it more clear, if the village had 100 family each Barber family will get 33 families as their clients).
Till my highschool, I never saw a haircutting salon. The barber used to come at my home every sunday. He was not paid in terms of money. He had his share in every harvest. Moreover, he would get gifts on festivals. Mariages and other rituals were impossible without him(still imposible). He was like a part of our family.
Similar relationship was with all Dhobi, Kahar, Chamar, Badhai etc. We were there clients for ages. And this relationship was such that there was no chance of any kind of untouchability.
There was only one exception. The Chamars. The physical contact was avoided with them because of their profession. But they were not socially irrelevant.
Brahmins were not allowed to eat cooked food of Shudras. And there was nothing derogatory in this. Brahmins had to follow countless other rules those were spiritually relevant for them only. Most of them were very difficult and non-Brahmins were excluded from them.
There is no inter Jati marriage among these Shudra Jatis. A Dhobi never gives his daughter to a Nai. A Nai would never accept the daughter of a Dhobi. If he does so he will be outcasted from his own community. Khatiks don’t make marriage relationship with Chamars. Chamras do not share food of Musahars. And this is not Untouchability.
But food and marriage or this whole social system was never a subject of antagonism among Jatis before a propaganda which has been going on unabated for last 4 generation forced people to believe that the only reason of their economic backwardness is this social structure.
Today, that ancient economic structure of villages has completely collapsed but Jatis prevail. The new generation knows nothing about the past. From school text book to cinema, they are given only one lesson- You were exploited by upper caste.
Never they get to know what happened to the traditional business of Chamars. Do Indians not wear shoes today? Why most of haircutting salons belongs to Muslims? Why do all the meat shops are owned by Muslim butchers? The whole vegetable market is dominated by Muslims, why?
There’s no need of research, no need of using brain. Just recital of one mantra ‘Brahmins have been looting non-Brahmins for ages, give temples to non-Brahmins’ will solve all the problems.