Storm that's why some of us are saying its not as easy as others make out.
An experienced cook will know if certain ingredients can be left out OR they can use a substitute. Using your examples I would sub
Mustard powder - depending on recipe turmeric or horseradish or even curry leaves. But it's a low perishable item so should keep well.
Capers - chopped green olives (I must admit I tend to have these in) but capers are a pickled item so should last ages UNLESS you introduce a sugar or protein to the jar.
Sour cream - (dead easy to make your own) again depends on recipe I'd sub with plain yogurt, Mayo or whisked cream cheese.
Tawdry - I think a lot of people do a mixture most days. I've met people who SAY they 'always cook totally from scratch' but use jar sauce (but have cooked the meat and veg for say a stir fry from scratch) or use easy cook rice, or pre cut veg etc.
I cook from scratch when my energy is there. I have mh issues and a physical disability so standing at a kitchen counter for 1 hour+ isn't always feasible. But I enjoy cooking and it soothes me so I do it when I can.
I make most sauces from scratch - except pesto (cause it would be hard to get enough basil where I am without spending a fortune to make a decent amount, plus pine nuts hard to get and it really doesn't taste as nice without) and hollandaise sauce (I don't know WHAT I do wrong it never works).
Do most of my veggies prepped from scratch except onions (I get far more eye problems than most such that it takes a couple hours till I can even see again!).
Meat and fish I can do but I can't do 'to order' without guidance as I'm veggie and I'm just not familiar enough. But I do all sorts with Quorn and soya meat subs and tofu.
I'm old enough to have done cookery lessons pre GCSE. In cookery lessons we did:
Victoria sponge
Swiss rolls
Christmas cake
Jam/lemon tarts (and made the jam and lemon curd fillings from scratch)
Mince pies
Lemon meringue pie
Shepherds pie (with piped mash topping)
Steak and kidney pudding (steamed at home)
Chicken chausseur
Hungarian ghoulash
Spaghetti bolognese (although we didn't make the pasta from scratch)
Quiche Lorraine
Scotch eggs and sausage rolls
I don't think schools teach any of this type of thing now.
At home I learned
Soups
Stews inc stovies
Loads of baking including fruit slices, bakewell tarts, ginger buns, tea loaf
Sunday roast
Breaded fish (Friday's) with proper home made chips and peas (at one point from a neighbour that grew them) we (siblings and I) loved getting messy and argued over who got to do the egg bit in the 'production line'
Glasgow fry (takes real skill to make the perfect fried egg with white cooked and yolk runny)
Savoury pies
Gravy from scratch
Steamed puddings
Custard from scratch (a friend once claimed they made their custard from scratch and I already knew they were quite a basic cook - they meant birds powder 😂)
Some cook books are better than others too. My now ex mil gave me (because it contained some favourite recipes of my then husbands cake and biscuit wise) a book by a tv cook (way before delia but after fanny) which not only included great easy to follow recipes but also had a fab section on things like how to prep certain veg (bear in mind it was written when Brits mainly ate potatoes, peas and carrots) and fruit, even how to do eg tomato 'roses', how to 'rescue' trickier recipes (a sort of troubleshooting section), basics for new cooks for eg how long to roast a chicken (by weight), how to make all the different pastries, a basic bread recipe... It was brilliant I'm bummed I lost it!
"I think modern life means that mothers don't have as much time to flop around in the kitchen showing their kids how stuff works"
That's possibly true in some cases but not the whole story. Have a look around here on mn there's a lot too many parents who think their children shouldn't have to do any chores at home. I've been called abusive for how much my dd does! (Occasionally she's agreed but doesn't really mean it). Because she's been cleaning her own room since starting high school, then doing her own laundry (admittedly that was earlier than I'd planned but on the back of an argument about me not being psychic re clothes required), she's been cooking with me since quite little for fun but around 13/14 usually cooked one evening meal a week. I've read comments like 'they'll have to do it enough once they leave home' 'their education is more important' 'I'll only end up doing it again properly' 'they'll make too much mess' yet how else are they meant to truly learn? They have to learn also to bounce back from mistakes and how to deal with them (eg dd panicking at first mixed wash mishap me then directing her to colour run remover and figuring out what caused it). I've also read numerous threads with older teens/early 20's "children" still at home and op despairing because they won't lift a finger - if you start young they get used to it, appreciate the work it takes, and take pride in their space.
"Some men claim not to be able to do these things, yet work executive jobs. I call bullshit on that." Definitely! It's a 'wifework' thing.
Quim - I wonder, a lot of older cooks seem to overcook, I wonder if that's at least partly due to modern equipment being more efficient than they're used to. My mother does the same now but I don't remember her food being overcooked when I was younger but it usually is now.
His father didn't even know how he took his tea! Every time they went to someone's house and he was asked he'd say 'ask the mrs'!
"The best chefs are men" ugh my dad comes out with that shit - he never cooked! To the point there's been times when mums been eg going into hospital and she's made his meals for the week PLATED and frozen and LABELLED (what they are AND day of the week it's to be eaten - but that's her 'thing' - if it's Tuesday it must be sausages type thing) so all he has to do is get out freezer in morning, microwave at night - and he struggled with that!
No, men GET to go far as chefs because as in so many careers to do well you need to be able to commit to extremely long hours, career breaks severely impact on career progression, it's a profession NOT known for flexibility for family reasons. But there are far more female chefs who work under the head chefs doing the graft!
Re beetroot - it can even be used to make a really lush chocolate sponge cake 😉