I don’t think they’re imperfections mate, more likely either...

I don’t think they’re imperfections mate, more likely either anchor points of some sort or services/alterations pending, an advantage you’ll have over conventional mortar is you can probably smack out blocks without compromise to anything above, the concrete lintels are ridiculous but the lesser of two evils here, steel is superior but the concrete solution exactly matches the blocks, you’d need to cut/shave 15mm off each block that sat on the steel otherwise.

Having said that, this is still an absolute shimozzle in my opinion, 30k savings on builds that have 30k (max) worth of block work? Keep an open/realistic mind mate.