Not to be overly pedantic, but preliminary reports are just that, and do not determine causes. There are certainly a bunch of factual observations about what transpired that will collectively be used to formally identify cause(s) and put forth safety recommendations, but it’s not over until it’s over…and it’s not over yet. Despite what is said here, I don’t see any evidence of anti-collision safety features in the ground radar system, and the report comments that such features would be useful - reinforcing that the system does not provide such warnings. However, that does seem a bit odd for a technically advanced ATC service as found in Japan, so it’ll be interesting to see the details in the final report.