Yep. Local supermarkets sell some drinks at lower prices than our wholesalers as loss leaders to get people in. They thus encourage the pre-drinking culture. We're a fizzy beer outlet in a town centre environment with trade actually increasing against the main trend but are sometimes in the position of having to refuse to serve folk who have just got out of the taxi at the front door 'cause their already pissed. The supermarkets are however never taken to task for any drink related incidents by the police or council as they can maintain a safe distance from the consequences of their discounted alcohol prices.
Anyhoo ... you're also right about the landlord and/or staff being able to make or break a place in a few days. We've been through a patch where we had an employee who wasn't a 'good fit' in the place - we got stopped in the street by regulars apologising for not coming in but also saying they weren't going to until he went. We now, by happy accident, have a superb team and the reverse applies.
Several remarks about driving to pubs. My kids are in their thirties - traditionally an age where they maybe have some disposable income. When I was that age we would drive out for a few pints, my kids and their mates absolutely won't, so if there's no other attraction like exceptional food, am exceptionally genial host ambiance or a beauty spot nearby, that trade has gone, and has been decreasing for years.
The 'sell real ale, keep it well and they will come' brigade are, well, just wrong. We shift an average of around 8 Kegs of Fosters, 20 odd of other lagers and ciders and one cask of ale a week.