The cheque circulaire isn't offered since 2010, that's explained at the bottom of the current fees.
Circular cheques are still being used. I just received one. The articles you link say that the circular cheques will remain when the postal orders are eliminated.
Your links were quite helpful. This looks like the most relevant bit for answering my question (from this article):
(en translation)
…According to the office of the Minister of Public Action and Modernization, Vanessa Matz was able, via the circular cheque, to guarantee a concrete and free cash alternative for the most vulnerable. In particular, this measure concerns those who do not have access to banking services or who are isolated. Neither circular cheques nor prepaid cards will be billed to beneficiaries, says the firm on Tuesday.
(fr original)
…Selon le cabinet de la ministre l’Action et de la Modernisation publiques, Vanessa Matz a pu, via le chèque circulaire, garantir une alternative cash concrète et gratuite pour les plus vulnérables. Cette mesure concerne en particulier ceux qui n’ont pas accès aux services bancaires ou qui sont isolés. Ni les chèques circulaires ni les cartes prépayées ne seront facturés aux bénéficiaires, précise le cabinet mardi.
That seems to explain what I was misunderstanding. I thought if the fee for cheque cashing is going away, perhaps so are the cheques. That would be very disturbing but that’s not the case. Apparently the 4€ fee is going away.🎉 I believe that fee was always illegal. Glad something was done about it.
Remaining question: how does a postal order differ from a circular cheque? What do we lose when postal orders go away? AFAICT, they function the same. This article seems to say circular cheques require movement -- going to a bank or post office to cash it, which is a problem for some handicaps. But I don’t get why that would not be the case with a postal order as well. How does a postal order get converted to cash? Is it perhaps about showing ID? Is it a case where a family member could cash a postal order for their grandparent, but not a cheque?