NJWirenut:
LFMC is approved for direct burial (2005, 350.10), provided it is marked as such. There is no mention to imbedded in concrete, either approved for or prohibited.
It also cannot be subject to physical damage, and a weedwacker, or a lawnmower sure can cause damage. Judging by the condition of some of the connectors, this has been around for a while.
350.30 (A) also jumps out; support.
