This is a very tricky quotation to understand and can best be understood if you know a little about word schemes in rhetoric. A common rhetorical literary device is parallelism, which has several subdivisions of kinds of parallelism. One kind of parallelism is that of antithesis.
Antithesis is parallelism between two clauses that express (1) contrary (i.e., oppositional) ideas or (2) contrasting (i.e., expressing unlikeness) ideas in a balanced, or paralleled, sentence. I always like the examples used by Kip Wheeler Ph.D. of Carson-Newman College, so I'll borrow his examples for antithesis:
Contrary antithesis, opposing evil and good: "Evil men fear authority; good men cherish it."
Contrasting antithesis, showing unlikeness between man's individual achievement and mankind's larger achievement: "One small step for a man, one giant leap for all mankind."
In the rhetorical literary device of antithesis, word order in the two paralleled clauses remains the same: evil men do something; good men do something [different].
Now, let's see what we have in our quotation. We may temporarily omit any distracting words or phrases in order to better see what rhetorical device underpins the meaning of the quotation we are trying to understand:
Oftentimes it is said that inflation is brought by unions, yet, how true is this, still inflation is the reason for the emergence of unions.
In order to get to the basic rhetorical structure, we can omit the beginning words and some words in the middle, leaving us with:
inflation is brought by unions ... inflation is the reason for the emergence of unions.
We have two statements that represent contrary, or opposing, ideas. In the first clause, "inflation is brought by unions," we have labor unions causing the development of inflation. This means that, in the economy spoken of, labor unions exist and that their labor demands drive the economy into an inflation.
In the contrary second clause, "inflation is the reason for the emergence of unions," we have inflation causing the creation of labor unions. This means that, in the economy spoken of, inflation exists (labor unions do not) and that its merciless strangle-hold drives laborers to create unions. In this economy, inflation exists before unions exist, therefore, unions cannot be the cause of inflation. In the second clause, inflation causes unions. This is contrary to the first clause in which unions cause inflation.
A clearer understanding of the rhetorically antithetical quotation begins to form in our minds now that we understand the parallelism of antithesis. A paraphrase of the quotation may help bring it more sharply into focus.
Whole Quotation Paraphrase:
Some people often say that inflation is caused by unions, which drive up costs with their demands, but, even though it is true that union demands drive up costs, nonetheless, inflation in the economy is the originating cause for laborers forming unions.
Discussion of Quotation:
Here we see a perceptive, humble, compassionate person making a statement converging two antithetical (opposite) views into one parallel non-accusatory statement that notwithstanding expresses truth in the face of complex logical fallacy. Joan Robinson is saying that while the case is true that labor union demands force rising inflation, it is inflation in the economy that causes exploited, undervalued and starving workers to form labor unions in a fight against industry barons who cause inflation before one labor union is born. In a beautifully crafted rhetorical sentence expressing parallel antithesis, economist Joan Robinson delivers a gently modulated diatribe against the greed of industry leaders while, in the same breath, defending the blameless laborers who sought refuge in unions.