As a consultant I never considered lunch as work because I could not bill a client for it. So to me at least 8-5 is 8 hours of work plus 1 hour break for lunch.
Consultant is a bit different than a salaried employee. I'm not sure how the language is structured in the US, but in Europe as a salaried employee, you're not producing X, you're providing labour. As in, you're hired to provide labour for 8 hours per day to an employer. The language used in our labour law is something like "employee is considered at work when present at location during time specified by employer and is providing his/her labour for use by the employer". You could skip lunch break if required, but most of the time it isn't.
That doesn't apply to all of Europe. In Norway salaried workers have a 40 hour week, but are only paid for 37,5 hours. The work day is 8 hours long, but you are not paid during the 30 minute lunch break.
It is also common to work from 8 to 4, but developers and others who are not too dependent on the outside world can have a bit more flexibility.
It is funny to see the shock in some foreigners when "nobody" is at the office after 4, when in fact they have already been at work for 8 hours.