I was genuinely surprised your comment doesn't end with an "/s", but anyway, I'd be interested to hear the rationale of users who pay for "smart people thoughts".
Most government tenders for a contract are available online, I'm from Australia so not entirely sure what I'm looking at but this[1] appears to be some sort of reference to the tender, although there is limited information provided.
Ever since xmlhttprequest (and even before that with images) we've been able to do server-side validation without a full page reload.
This "solution" completely ignores the purpose of client-side validation which is to a) reduce load on server-side resources, b) validate faster without the network latency and c) validate more securely and privately by not sending the content to the server.
imo, "modern" would mean it removes or replaces features and characteristics which were exclusive to or popular in a previous time period but are not essential or can be replaced with "modern" alternatives.