Max needs to treat his car with the same respect he
shows the other drivers
That would only make the problem worse, as he doesn't respect the other drivers at all...
While I am not convinced that Max is entirely to blame for the large number of mechanical issues, he does make a lot of errors in his driving, and the sort he makes tend to be the sort that damage cars.
Max is Helmut Marko's "golden boy" - he was hired into the group because Helmut believed him to be the epitome of what being a Red Bull driver is all about, and now neither of them are willing to accept any evidence that he is not. The Verstappens don't have Helmut over a barrel directly, but if Helmut's declarations are irrefutably proved wrong, he stands to lose a lot of face in the company and it would put his position as Dietrich Mateschitz's trusted consigliere at risk. Not because Max was proven wrong, but because the philosophy Helmut endorses and Max embodies had been proven wrong. Put simply, Helmut has too much pride, power and possibly even friendship on the line to replace Max voluntarily. Where Helmut goes, the entire Red Bull family is obliged to follow, due to the "my way or the highway" attitudes there.
Anyone else would have been removed from Red Bull entirely had they been kicked out of Toro Rosso mid-season, but the "golden boy" pride led to the welcome mat being issued to Red Bull instead, that would have been better given to Carlos Sainz (assuming it was even necessary to demote Daniil Kyvat - something of which I am not convinced, and ruined his career). Anyone else would have got into serious trouble for the number of pointless collisions Max has done.
As for Singapore 2008, I believe Fernando was deliberately kept in the dark about the nature of his "miracle". He really doesn't know how to keep a secret, and so if he had found out - or even suspected - there was skulduggery afoot, it would have been round the paddock before you could say "Not another spying incident!" Also, after feeling backstabbed by McLaren, there would have been the risk of Fernando simply reporting the whole thing to the FIA before or immediately after the cheating was enacted (remember his doing exactly that at the wrong moment for McLaren was what turned a close squeak into a bruising penalty). In short, Fernando is too loose a cannon for any cheater to have deliberately confided in him.
The only one who might have confided accidentally - Nelson Piquet Jr - was, I suspect, too intimidated by his team-mate to start casual conversation that was the least bit risky (we already know, from his own testimony, he was intimidated by the power of senior figures at Renault in general). If I recall correctly, Fernando wasn't in the room when Nelson initially came up with the ridiculous idea. So, however implausible it may seem, I think Fernando genuinely didn't know his win in Singapore 2008 had relied on dishonesty until he was informed of it by the FIA. (As for why he still insists his victory was fair... ...well, he didn't cheat himself and I've seen no evidence he knew, let alone contributed to, the cheat, so he's hardly going to renounce the validity of his win even if the rest of us think he is wrong...)
In the UK, guilt by association is not possible, but it is possible to be convicted of conspiracy to commit crime. This requires a higher level of intervention - either something not reported that should have been (which was why Witness X needed indemnity under the 2003 anonymity rule in order to safely report the incident almost a year later) or actual contribution to the planning or execution of a crime. Simply being in the same team, or even simply benefitting from the crime, is not enough (unless a corporate charge is laid on, which is not much help in a market as mobile as F1's).