As you might surmise, I am no expert on butchering.

I was thinking that the shops of Highbury would have old fashioned, tax effective, small windows rather than modern (for then) bow or display windows - so the children were able to eye the gingerbread, but Emma, on the other side of the street, could only have a clear view of the children. Of course, either is possible, but I would have thought that as Highbury is not a market town, and the tradespeople are servicing a captive population, they would not feel much need to make renovations, or to build new premises.
And for the butcher, I thought the law applied (if it had not been repealed) to any butchers shop or stall, with additional regulations as to slaughter and displaying hides, so that if he had a shop, it would be in a lane off the high street, rather than on the high street.
The plain, practical enamel tray is an innovation as well (although enameling had been around since ancient times, techniques for enameling sheet iron were developed at the beginning of the industrial revolution) - the butchers tray might have been wooden, but I figured a new tray might be a possibility.
Of course, if it were 1850, I would simply have assumed it was all as you say.