The demise of good 'bubble'!

There isn't a shortage of cafes in London but there are very few who serve good 'bubble & squeak'. Maria's in Borough Market and Terry's in Great Suffolk Street are two exceptions but on the whole the standards have dropped.
I have my own opinions on what should and should not be in 'bubble', the shoulds are potato, cabbage and maybe onion? the should nots are peas, frozen mixed veg, mashed potato. I have recently been served fried packet mashed potato (in a cafe in Deptford Market) and frozen 'Birds Eye' bubble cakes! (in a cafe in Holloway Road), but the worst I have ever had was in a cafe in Finsbury Park, the cabbage was sour!!
What has happened to a classic, traditional dish?