I read that article and was quite shocked. As I read it, it seemed to have undertones of a mis-selling scandal. If I remember rightly, the person in the article opted not to buy the leasehold at the first opportunity because of a lack of funds available at the time (just moved house, quite understandable), but then was stung with an offer multiple times higher a few years later when she was in a better position to buy it. I dare say that if they had been properly advised in the first case about how the price could change in the future, they would have looked a bit harder to buy the leasehold upfront.
At some point people have to take responsibility for their own actions. In the case you mention it is unfortunate, but they should have taken some advice on the initial offer. It's not the company's responsibility to force people to have common sense and get some advice on a situation.
Generally I agree with you a lot on that point - but at the same time a company have a responsibility IMO not to knowingly profit on other people's ignorance - thin line there from doing business and scamming people.
the owners should at the bare minimum have the same rights as a leasehold flat.
Do you (usually) get the option to buy the leasehold when you buy a new build?
No, they don't provide the option to you.
No this is wrong they do absolutely offer this.
Not at the time of purchase.