What apology are you thinking of? The thing I find when I search for that is CEO Tony Hayward's statement of 17 June 2010: https://www.theguardian.com/business/2010/jun/17/bp-tony-hay...
That specifically doesn't admit the mistake or take responsibility.
You can find further discussion of their apologies here, and they get a 3/10 rating for apologizing well: https://www.perfectapology.com/BP-oil-spill-apology.html
I don't think anyone would say an apology is sufficient response. It's only a necessary component of a full response. But if a company screws up the apology right off the bat (as so many companies do), you can tell that things are not going to turn out well for them. So it's pretty interesting that so many companies (and individuals) write such bad apologies, so much so that it's pretty rare to see an apology even as good as this one.
This doesn’t really mean much by itself. These are elements of the BP apology for the gulf spill as well. The only thing that matters is actions taken. Anything else is fluff part of standard PR.