I think that offering gratuities to police officers moves the line of corruption too close for any type of comfort.  Even if the person offering is doing so because of a generous nature and doesn't expect anything in return, I think that it moves the line too close.  It seems that such a situation is bound to result in preferential treatment or where some type of quid pro quo is expected.  At the same time, I think that this is part of the trapping of power and seems almost inevitable.  It is not something that can be dismissed, bu it is so prevalent throughout the world and permitted in so many contexts that it is very difficult to stamp out.

Your definition of "gratuity" would be very helpful here.  If by gratuity, you mean taking something extra (like money) at the end of performing a service, then I agree that this borders on bribery, which is unlawful.

On the other hand, many Starbucks, for example, have the policy to serve free coffee to anyone in uniform.  I understand it was a managerial decision unique to each store, but this was certainly the case at the two Starbucks in Waco, TX.  If this is what you mean, then I do not see anything wrong with this.  In fact, it is a win-win for both the company and the officer.  Officers get free coffee, and Starbucks has a consistent and regular police presence.  This sends a message to the neighborhood that Starbucks is attempting to promote safety as well as thank services that largely go underpaid.  (I used to constantly ask for a teacher discount to no avail...)

I believe that the acceptance of gratuities by police officers may be considered bribery to an extent, depending on what it is they are getting. This would apply to money especially. Police officers get paid to do a job and that is protect the citizens, etc. so I really do not see that gratuities are acceptable since they are already getting paid to do their jobs.

When I was a teenager I worked at a fast food restaurant and a local police officer would escort us to our cars at night for safety. In return, we would always have some food and a soda to say thank you. I think this is okay but if we are talking about money then it may be seen in the wrong way and make the police officers look bad. I guess it really all depends on what the officer is getting and for what purpose.

You mean gratuities like having shop owners give them free food or things like that?

I think that something like that is probably not a good idea -- I think that it at least gives the appearance of corruption.

Now, I would think that it would be okay if a restaurant, for example, wanted to have something like a 10% off deal for all police.  I do not think that would be bad.  The reason is because it would be a set discount and would not be negotiable.  But if you start giving away free stuff or payments without any clear cap, then the police might start to demand more.  It would also look more like bribery and less like a simple token of appreciation.