There is a difference between what is common practice among a particular group of people and what their formal religion has ordained them to do.
If your question concerns the latter then there are a few things that need to be considered before it can be determined whether it is permissible/Halal or not.
if food that is being taken is not know to contain meat, fat content and their derivatives, then it's permissible, provided it's Halal and that alcohol is not being consumed at your table.
if food that is being taken does contain meat, of a Halal, non-marine, animal.
- the place where the meat was produced doesn't have Muslims in majority
- restaurant is run by a non Muslim then it is not permissible (provided it is not known that producer of the meat being taken is a Muslim, else permissible)
- restaurant is run by a Muslim then it is permissible
- the place where the meat was produced does have Muslims in majority, the restaurant is run by non-Muslim (permissible it run by Muslim)
- it is not known whether the producer, more precisely the person who slaughtered the animal, of the meat is a Muslim or not, then it is permissible
- it is known that the producer is Muslim then it is permissible
- the producer is non-Muslim then it is not permissible.
The writings/Halal certifications have no value whatsoever.