What kind of scenario do you have in mind? I work 2 miles from where I live, so I reckon I could walk home. I have loads of stuff at home. When I am further away I carry more stuff on me. I'd also be willing to ask for help, whether from friends who live near-by, from the police, or from strangers. My town is not prone to earthquakes, hurricanes, tornados or volcanoes. If my town did happen to be hit by, eg, a terrorist nuke, there are plenty of other towns near by. England is a densely populated country.

Anyway... for me the biggest difference is the knife. In the wilds you may need to do a lot of working with wood, eg building a shelter, carving tools or splitting logs for a fire. In the city we are surounded by buildings, tools and combustible material. A small knife is still useful, but screwdrivers and other tools are more important. Also, of course, there may be legal issues. So I don't carry a big fixed-blade knife in the city.

Fire starting, well, I'm surrounded by houses I'm not going to die of hypothermia. I'm also surrounded by people and half of them smoke so carry ciggarette lighters. I do carry my own fire making but that's more for convenience and back-up.

For water purification, you can always boil it. There's no shortage of pans. Most houses will have a reserve sitting in their pipes and hot water tanks, and more in their central heating systems. I supplement that by stock-piling bottled water at home.

I add, money and a mobile phone - one with internet access. Multitools. There is more emphasis on light (through fear of being stuck in a windowless building in a powercut).