What the newspapers need is something like ASCAP that can act as a single revenue management entity for microtransactions. What no one wants is to have 30 news subscriptions, and so what actually happens is everyone has ~zero news subscriptions. It's happening with video now too as Disney+, HBO, Prime, Netflix, etc. are each fighting over limited monthly subscriptions to segmented markets as opposed to Spotify, Pandora, etc. being gateways to one large market.
I don't know the details of how or why ASCAP has managed to do for the music industry what pretty much no other industry has been able to achieve. ASCAP isn't even exclusively licensed.
I think this might actually be the innovation here. Artists can use their normal distribution channels, and also sign up for ASCAP because, why not, it's free money. If enough people do this, they become a very useful distributor simply due to the size of their catalog.
Is this really true though? Aren't ad prices very very low, how much do those dubious ads pay that appear next to the articles we read? Surely not that much?
They'll do whatever it can to make a penny in this cutthroat industry and especially on mobile, so losing a significant portion on transaction fees is better than nothing to them.
In other industries, it's better to maximize your transactions ROI and reduce them to a minimum, even if it means making the payment a bigger amount that covers a longer subscription period. They'll even offer a promotional rate if you take a yearly subscription instead of monthly.
Micropayments are a hassle for any system that has people, actual human organisms, being responsible for a gazillion of small transactions. The involvement of a human increases the cost of each money transaction. Only for detecting and resolving fraud a human needs to spend minutes and hours of his life, his boss has to pay him at the end of the day, and that cost bubbles up to the consumer. Minimum fees have be to many cents or dollars for each transaction, so the micropayment starts to not being a micropayment, it starts to seem very much like a payment.
The only solution to that, is a fully automated money transfer mechanism, an immutable public ledger with all the pseudonymous transactions, i.e. bitcoin. The miner network ensures the validity of the transactions, that no malicious actor in the whole network change one bit of a transaction to his benefit. Humans can do that, have done that for centuries in the banking system, by hiring trusted employees, and by following protocols to ensure the validity of each transaction, papers with stamps and all of that.
Micropayments can help for a person to change a light in the street, and charging all the residents around, a thousand of them, for 1 cent each. 10 dollars he will receive in total, 5 dollars for his work, 5 for the light bulb, and he will be paid the minute the work is done. No need to give a corrupt politician 10 million dollars, for all the work in his municipality, and the politician afterwards he will pay the technician for the fixing of the light. That creates a honey pot ready to be exploited. Micropayments can make that honeypot disappear.
Consumers despise paying for usage. They'd rather pay a monthly fee and have unlimited usage.
Which is generally how games do it
If I pay for something with a credit card, that's a payment transaction. It also involves (a whole chain of) IOUs.
When you visit any website, a dozen or so companies are charged tiny amounts of money for showing their ads to you. Charging a single entity, the reader, is much less complicated. So it's not a technical limitation.
Their independence/neutrality is the key differentiator.
A better version of your question is – why do newspapers charge for a monthly subscription instead of a per-article fee? The simple reason is that the numbers just don't work out. They'd have to charge a lot per article and have people pay for a lot of them to break even with the current subscription or ad-supported model, and that's not going to happen. And even if it does, there would just be too much day-to-day variance in sales. The reason subscriptions are popular is that businesses like a steady, predictable stream of revenue.