As kids club slammed by angry mother, we ask: would you let your child travel alone in a taxi?

A row has erupted after a mother slammed a kids club for sending her children to travel alone in a taxi.
The mother, who took to mumsnet to vent her anger, said in her post: "Kids went to holiday club today, they have been many times before, they know the staff and the staff know them.
"In the afternoon they go swimming off site. Today apparently there wasn’t enough room in the minibus for all of them, so my two (aged 8 and 11) and two other kids (don’t know the ages) went in a taxi by themselves. No adult from holiday club in there with them, but using a known and trusted taxi company."
The mother added: "I’m not happy about it. I’d never put the kids in a taxi on their own, and don’t like the fact that the holiday club have done it without me knowing."
She then asked: "Am I over reacting?"
The responses the mother received were very mixed, with some people supporting her viewpoint, stating that staff at the kids club should have asked her permission first. However others were less supportive, accusing her of over-reacting.
With all members of the public who work with children requiring an enhanced Disclosure Barring Service (DBS) check, should the mother have been concerned given that the same DBS checks would have been performed on the driver of the taxi?
Those working within the taxi industry routinely carry lone children and vulnerable members of the community, and are generally trusted by local authorities and the wider public to perform their duties safely.
So, was the mother right in expressing concern that her children were put into a taxi without a supervising adult, and would you let your child travel alone in a taxi?
Image Source: LEVC