I have also worked as a PM in industrial projects, I was shocked by standards of professional behaviour I encountered in house building. Presumably it’s different with large sites and major contractors but for one off jobs like self builds, many providers just don’t care, maybe assuming they won’t get more work from us.
My appointed SE also disappeared after initial quotes, one site meeting and a preliminary schedule of works. He was also contracted to provide a PC certificate but failed to perform the first inspection. After many more attempts to contact him, I was forced to find another SE to take over.