There are multiple issues going on.
The big one is, that you can have rights, but how they are implemented and enforced in practice - the unspoken aspects of it - really are crucial in determining what your real situation is, and your safety or potential risks in exercising those rights.
For example - in some countries you have free speech and freedom - except that you may lose your job, or be taken by secret police if you actually try to use those rights. In others, there are strong incentives that steer companies controlling the media or publication, so that rights are again, hard to really exercise.
It's not a free press if exercising that freedom in good faith risks you getting pejorative treatment, any more than it is encouraging whistleblowing, to have a whistleblowers charter in a company but realistically your career dead-ends anyway and the matter gets hushed up and you described as a problematic troublemaker. In many cases you can fight back legally if treated wrongly, but in others you can't (or its difficult to: money, standing, whatever), and for real press freedom you shouldn't have to.
So when you look at how a country is rated for freedom of the press, you have to nearly ignore the rights people * should * have according to their country's laws and constitutions, because those will almost always say it's fine and great. You have to go by what actually happens on the ground, not what's claimed to be the case or should be the case.
So you look at things more in this kind of way: When journalists come across a story that's negative or harmful to some powerful interest (person, police, govt body, politician), or could be seen as threatening them by suggesting they aren't okay in some way (they treat workers badly, they committed genocide, they're institutionally racist, they broke their own laws or committed illegal acts). Or they've reported on a foreign matter in which their govt has some involvement, or talked down their own or another country/states. How does the country actually treat them?
Will it block them at the borders? Arrest them (many places)? Charge them with defaming the nation? Revoke their right to attend press conferences? Harass them? Pressure the employer to fire or discipline them, or dissociate itself from their reports (subtly or not so subtly), or begin an "investigation" into "irregularities" at the employer such as tax related? Consider them legitimate targets for surveillance/tapping? Or what? What about foreign journalists?
Unfortunately in that light, many countries that you'd think do well, actually don't. Because its in those kinds of cases, that press freedom is really tested and able to be seen (or not) for what it really is.
- Update: The saying that "It's the exception that proves the rule" is very relevant here. The word "proves" in this saying has its olden-day meaning of "tests" (as in the expression "put to the proof") - it is the exceptions and edge cases that really test and demonstrate how "real" a rule or belief is, not the regular ordinary cases which anyone can point to and say "see? it's fine".