Ground on power supplies
Here comes the long story.

A SMPS is a rather complex circuit considering the rather simple and common task it is performing. Generating a low noise and constant DC voltage from mains AC voltage. 

It consists of several blocks


mains filtering
power factor correction
converter
control circuit
output filtering


In design of these blocks there are a lot of constraints between them but also a some of degrees of freedom. In the center of a SMPS is the converter which can be designed adhering to different principles (buck, Cuk, SEPIC, just to name some very common ones). Also within a converter of a single type there can be variations in parameters affecting


ripple
stability
overload handling
brownout behaviour


To sum it up, building a SMPS delivering 19V DC with 1.82 A, 0.5 V output ripple and at least 0.85 efficiency there are a lot of different designs around with a lot of varying other properties.

A lot of difference lies in EMC behaviour. So for the one design it may be beneficial to ground something inside the SMPS while for another it might be detremential.

Why are there now SMPS with and w/o grounding for a single appliance?

Companies like Toshiba and LG don't design the SMPS themselves, it is not their core business. They source it from more than one supplier to keep their supply chain redundant. Many SMPS manufacturers have specialised in certain converter concepts. They supply "their" concept for the cheapest price and with optimisations at their best. 

LG and Toshiba then don't care about uniformity of the SMPS they put into the boxes. They aren't Apple after all.