That’s actually a misconception. Sure, Protoss can produce workers faster if chronoboosted (about 50% faster than typical production time for 20s, with a chronoboost being roughly available once per minut), but that’s only a 10% boost to workers production (5.6 workers per minut instead of 5) supposing you’d only CB your nexuses.
Yet in fact, the superiority of Protoss’ economy doesn’t comes from this 10% boost, but from the fact nearly no worker time is lost during the construction of buildings, while you have -1 worker per building in construction for the two other races. And that means a temporary +1 worker/per constructed building for vs Terran, and a permanent +1 worker/constructed building vs Zerg.
And this last reason is why, in the first minuts of a standard game, Protoss do have equal to more workers than Zerg at first, despite Zerg being the fastest race at producing workers. Then at some point depending on the build used, the workers curves will cross and, if left undisturbed, will get the worker lead.
According to Liquipedia, a MULE returns 5x more than an SCV per each trip ; but takes 3.85x more time per trip. So that means they’re only 30% more efficient than SCVs, not 6 times more. Yet, they work like +1.3 worker regardless of the patchs’ saturation, so the income boost compared to a regular worker increases greatly with the base’s saturation. Liquipedia settles for around 3.5x more efficient than a regular worker overall.
As we said, Chronoboost is in fact not the main factor in Protoss’ economy relative speed/efficiency compared to others. So even while purely chronoboosting upgrades or units, they would still retain that efficiency.
Furthermore, as you said, larvae can be spend on army as well. Yet you forgot that CC’s energy also can be spent tactically on scans instead of economy. So all three races have strategical choices to make there.
It depends a lot of said harassment. If your harasser (let’s say a scout) deals 5 dmg per shot, then drones would in fact have the same durability than SCV’s due to them regenerating 1 HP from the very first second they are hit. And probes can regenerate faster than any worker after a few seconds.
Yet, all those come to nothing against damage sufficient to oneshot (or even two shot with enough margin) probes or drones. Hence the durability advantage of SCVs against mines or oracles.
Yet, the workers that are the most vulnerable to harassment aren’t probes nor SCV’s, but most of the time drones due to the lack of wall. You’d have to go for a way to bypass walls in order to kill probes or SCV’s, most of the time.
And then, if you’ve got an harassment tool bypassing walls, SCV’s durability would indeed give them an edge over probes.
Yet, probes can be produced faster than SCVs, and drones can be produced faster than probes. So overall, things would balance themselves out if taking worker harass in account.
You missed the superior worker efficiency due to the worker time lost by the other races. And that zerg workers are the most vulnerable. Yet technically, vs terrans, to me that paragraphs seems true.
There’s also another fundamental that comes into play, which is the expansions’ timings. Zerg expand fastest, with Protoss second, and Terran arguably the slower (though some risky builds can mitigate that, those being riskier vs protoss). So Protoss being able to land their third base before Terran in PvT, even more combined to the production stalls due to CCs being morphed into OCs, gives them even more edge in that regard.
And that is why the devs often mentioned protoss 3rd bases timings, as they’d want it more defendable vs Z, and not too quick vs terran (which was one of the determinants of the stim timing buff). And why mines superior efficiency vs protoss is one of the aspects that balances things out.
Ultimately, undisturbed,at 6:00 mark :
— Zerg can be 70-72 workers high (standard B3 speedlings build)
— Protoss can be 60-62 workers high (standard gate expand SG B3)
— Terran can be 48-50 workers high +2MULEs ≈ 54-56 (2-1-1 standard B3)
From there the incentive for Protoss to harass Zergs, and for Terrans to harass both Protoss and Zerg. And that doesn’t even takes in account the different economic efficiencies.
To sum things up :
- Workers production rate : Z > P > T.
- Economy efficiency : P > T > Z.
- Harassment worker vulnerability : Z > P > T.
Hence why the pressure to harass in each MU is often on the Terrans’ side, and why those three components would balance themselves out with proper harassment. 
Hate can come from fear, which is primitively triggered by ignorance. The less you know about something different, the more you’ll be likely to fear it, then to hate it (same mechanism than racism, sadly on the foreground of current international actualities). That’s part why so much battlenet forums single race players seem to hate so deeply one race, and why they whine too much over it : ignorance of concerned race → fear → hate. And by that, ignorance of the tools they’d have to deal with their opponents.