More or less... or fewer?

In the grand scheme of things, we Anglophones tend to speak how the words come out and we don't really go in for precision or pedantry when it comes to grammar rules - we leave that to the French. But there is one area which is becoming increasingly contentious: the use of "less" is starting to replace "fewer" to the latter's detriment, and some are finding it hard to accept. Including me.

When we decided to have two words to describe a reduction in something, it was for good reason, even though it was, to put not too fine a point on it, unnecessary. In English, the word "fewer" is the opposite of the word "more". But so is "less". So why the need for two words? Because we still have things that are countable and things that are uncountable. We also say "how much?" and "how many?" for the same reason. And this is where the confusion comes from.

When we say "how much does this cost?" what are we implying? And why not "how many"?
Because we can count pounds, dollars and euro, but not money as a concept. So we're asking "how much [money] does it cost?"

The same goes for light, time, sand, paint, water, wood and snow. We can't count them as a concept.
But we can count the number of lights, the number of minutes, grains or buckets of sand, litres of paint, glasses of water, blocks of wood and centimetres of snow.

So naturally, a language like English, which is owned by both no-one and everyone at the same time, will allow flexibility in fluent speech - mistakes like confusing "less" and "fewer" are going to happen. And that is fair enough.

But not in written language - it just looks unprofessional. When I see a quantity/number mistake on a website trying to sell me something, it comes across as sloppy to the point of off-putting. Like the "ten items or less" signs at some supermarket checkouts.

Here is a chart to help you:

NUMBER = implies a grouping of things you can count, e.g.

the number of chickens on a farm
the number of words on a page
the number of bottles of beer drunk at a festival
the number of people on a bus
the number of times you eat per day

AMOUNT = implies there's a volume, so you can't count it, e.g.

the amount of time to sail from Dover to Calais
the amount of water needed to fill a pond
the amount of sugar in every cola bottle
the amount of noise your neighbours make
the amount of yellow paint needed to change blue to green

So....

I have a lot of chickens, you have fewer chickens than me, but you have more sheep.
There are 459 words on this page, many of them are conjunctions and articles.
25,989 bottles of beer were drunk at the festival, quite a lot fewer than last year.
There are 44 people on the bus, 22 standing and the same number sitting.
She eats only breakfast, lunch and dinner, but he eats two or three snacks between mealtimes.

It takes 1 hour 45 minutes to sail to Calais, but the tunnel takes far less time.
I use more water to fill my pond than to have a shower, but less water than it takes to fill my swimming pool.
There is a smaller amount sugar in a Mars bar than in a can of cola.
A fleet of aircraft makes less noise than my neighbours.
You need 3 parts blue, 2 parts yellow to make a leaf green colour, but use more yellow for olive green.

More is the odd one out, because it's for both countable and uncountable things.

COUNTABLE:
(number)
The most - many/a lot of - fewer - a few - few - the fewest


UNCOUNTABLE:
(amount)
The most - much/a lot of - less - a little - little - the least