Those aren't necessarily inherent flaws, they're bad execution. Ride-sharing _can_ be very profitable, but it's also supposed to be very low-overhead. SV startups don't do low-overhead.
Electric scooters are a little iffier, as they take significantly more capex and there isn't much data on market acceptance (Or, at least, none of which I know.)
Meal-in-a-box is not a bad idea either; new people are showing up every day whining about how, "Adult-ing is hard." The fact that people eventually "graduate" is not an issue so long as more people are being born. It's just not necessarily something Joe Six-Pack is going to buy.
If you've noticed a common theme here, it's that the idea of hyper-scaling can be flawed. The above all have significantly lower threshold for market saturation than they believe, if you ask me.
Ride-sharing can be successful, but may not take over the world. Electric scooters can be successful, but may not take over the world. Meal-in-a-box can be successful, but may not take over the world.
SV gets stuck in the pareto trap of scaling past economies of scale and to the point where that next 20% of your customer base takes 80% of your capital. You can push scaling, but the market only moves so fast.
Ride sharing is only viable if the market shrug off all the externalities (insurance, traffic management, personal data security, etc) and keep pumping money into it in the hopes of fully autonomous vehicles becoming a reality within the next decade. Indeed if this type of hyperscaling were profitable we should have seen major regional taxi operators like airlines in developed countries a long time go, but alas there never was because it was not a good idea then and now.
Ditto for electric scooters - I rarely see anybody use one but it is somehow already costing my country millions in medical costs.
The housing mortgage crisis, dot com boom and bust, payday loan industry, for-profit universities, fad diet companies, supplements with no scientific basis, cigarette manufacturers... There are whole industries and periods of time where large numbers of shady companies are rising and falling.
This was an issue of bad timing, not a bad business model. People weren't really mentally at the point of buying such thing on-line, and pets.com burnt through their cash so quickly that it couldn't wait for people to start adopting it. As pointed out by others, Amazon made it work; however, they are very smart about diversifying, re-investing, and not being profligate with cash-on-hand.
The rideshare industry famously doesn’t make a profit.
Neither does the electric scooter industry.
The meal in a box industry has retention problems, because eventually their customers learn to shop and cook.