The greatest financial surprises are buried in the ground. A soil survey reduces the risk of sliding into additional financing even before the first stone is laid.
Moreover, it benefits the "liability chain" because without the earthworks engineer and structural engineer, people tend to go on the barricades. In case of doubt, you then pay for this in the form of risk premiums (more concrete, more steel).
Without a soil survey, our drilling for geothermal energy would not have been approvable, nor the use of recycled gravel (savings of 2,000€) under the slab. It was also necessary to prove that on-site infiltration of rainwater is not possible in order to be allowed to connect to the sewer.
For me, there is no discussion, a soil survey on your own property is a must (before purchase!).