In circumstances such as those in the main proceedings, do Directive 77/388/EEC and Directive 2006/112/EC preclude national legislation or a tax practice according to which the reverse charge mechanism (simplification measures) — which was at the time mandatory for transactions, relating to land, between taxable persons for VAT purposes — is not applicable to a person who has been subject to an investigation and registered, automatically, for VAT purposes following that investigation, on the grounds that that person had not applied for or been granted registration before the transactions were carried out or the ceiling [for exemption] was exceeded?