Because at a local Target your exposure risk is determined by the local spread of the virus... if your in a low spread area, your risk is lower. The smaller the area, the less people traveling in and out of it limits the spread of the virus. Also as mentioned, people spend a short amount of time in the exposure situation.
To go on a trip to Disney/Universal means traveling outside your home risk zone in to a current hot spot, also increased exposure traveling on planes, eating at restaurants, hotels, gas stations, etc. And then multiply that by all the visitors coming from all different locations. And THEN you have all those people leaving and going back to their home zones possibly upping the exposure there. Yes, masks and distancing improves your odds of staying safe..but in one situation you have multitudes more factors adding to the risk.
Granted, it only takes 1 person to spread the virus in either location...but the odds are generally lower of running in to that person the less factors you allow that contribute to the spread.