The best software should be invisible

I’ve just bought some wine and dinner in Tescos supermarket and paid with a self-service checkout,

I forgot about it,
Then I started thinking about how much easier Tesco’s self-service checkouts are compared to the Sainsbury’s ones I have used twice over the past week, buying something similar.
Start off with the fact that I don’t expect to use my brain when I go to supermarkets, at least the logical part of my brain. I think hard at work and go to supermarkets when I am not at work, so trying to rest my brain. I can cope with a smile at a check-out attendant and sometimes some chat and taking my card out that’s it. I don’t expect to have to work out how to use software.
I don’t like social interaction much when I need to get something out of it. I have to do that a lot at work, which is fine, but I don’t expect to have to do it at supermarkets. So I hate it when the software bleeps at me and I have to find someone to type in a password (which is all they do, by the way, never do what the software is asking them to do, ie confirm i’ve put what i said i put in my ‘bagging area’).
The first time I went to Sainsbury’s on the weekend, I had to get an attendant twice – once to confirm I had in fact bought one bag, and once to confirm I’d put a pencil sharpener in the ‘bagging area’ which was too light for the scales to pick up (not that the software was clever enough to know).
The second time I had to get an attendant 3 times. The first time I put the shopping basket in the “bagging area” and think I couldn’t just remove it, someone had to type in a code. The second time to confirm I was over 18 to buy wine. A third time to confirm I had bought 1 bag.
In Tescos I bought 1 bag and bought wine and didn’t need anyone to type in any codes.
A third example – when buying a chocolate bar in an airport last weekend, already stressed from having to look after 3 small children and bags (with my wife’s help), I was faced with a self checkout machine. An attendant came over and (perhaps seeing the look in my face or perhaps he does it to everyone) agreed to operate the machine for me. That was great for me but from the software’s point of view, is pretty much admitting defeat.
It is much easier to use software when you know how it works and you know its quirks and bugs – just like the people who build it do. It is horrible to use it, particularly when you don’t want to use your brain.
The relevance to the Software for Domain Experts blog is this. Experts don’t want to think about their software – they don’t even want to feel that they are using software.
Making software which does this is hard – but worth the effort.
When will someone do this for experts?