... playing and watching them makes people happy and positive.

[tzfujimino]

Wheelchair tennis is an exciting Paralympic sport. Japan has some really famous players. One example is Kunieda Shingo. He has won many world championships. I watched some videos of his matches. I was amazed at his power and speed. However, Mr. Kunieda says, "Sometimes people say playing tennis in a wheelchair is amazing. It makes me uncomfortable. We're playing tennis just like other people." Another well-known player is Kamiji Yui. She became the youngest Grand Slam winner in 2014. She once said, "I want to keep smiling when I play. Smiles keep me positive." Her smiles keep us positive, too. These two players remind us of the power of sports. Everyone can enjoy sports, and playing and watching them makes people happy and positive.

(Source: NEW HORIZON English Course 3, Tokyo Shoseki, p12)

The verb in the last sentence in bold is in the singular ('makes').
Is it because 'playing and watching them(=sports)' is considered as a unit of activity/combined act, as in Drinking and driving is illegal?

 

[Tarheel]

Yes, I think you are right that they see them (playing and watching) as a combination. (But I don't see how.)

 

[jutfrank]

It isn't quite the same as 'drinking and driving' (which means drinking and then driving) but yes, we can say that the person who wrote that sentence was thinking of the two activities as one combined thing.

 

[tzfujimino]

It isn't quite the same as 'drinking and driving' (which means drinking and then driving) but yes, we can say that the person who wrote that sentence was thinking of the two activities as one combined thing.

If you were the writer, which form would you use in that sentence, the singular or the plural?

 

[emsr2d2]

If I were writing it, I'd probably be careful and use "make". However, in casual everyday speech, I'm quite likely to say "Playing and watching tennis makes me very happy!"

 

[jutfrank]

If you were the writer, which form would you use in that sentence, the singular or the plural?

The singular, I think.

I suspect the logic here may be that the speaker means something like 'playing and/or watching' rather than seeing them as a conjunction of two acitivities. With or, the singular is the only option. I have a feeling this disjunction in the speaker's mind may have biased the choice of the singular. I don't know.